diff --git a/datastorage.lua b/datastorage.lua
index 8f20a6b68..14966c5e2 100644
--- a/datastorage.lua
+++ b/datastorage.lua
@@ -42,6 +42,9 @@ function DataStorage:getSettingsDir()
     return self:getDataDir() .. "/settings"
 end
 
+function DataStorage:getDocSettingsDir()
+    return self:getDataDir() .. "/docsettings"
+end
 
 function DataStorage:getFullDataDir()
     if full_data_dir then return full_data_dir end
@@ -58,8 +61,8 @@ end
 local function initDataDir()
     local sub_data_dirs = {
         "cache", "clipboard",
-        "data", "data/dict", "data/tessdata",
-        "history", "ota", "plugins",
+        "data", "data/dict", "data/tessdata", "docsettings",
+        "history", "ota", "patches", "plugins",
         "screenshots", "settings", "styletweaks",
     }
     for _, dir in ipairs(sub_data_dirs) do
diff --git a/frontend/docsettings.lua b/frontend/docsettings.lua
index ca49711a5..14cfd4c5d 100644
--- a/frontend/docsettings.lua
+++ b/frontend/docsettings.lua
@@ -15,6 +15,7 @@ local util = require("util")
 local DocSettings = LuaSettings:extend{}
 
 local HISTORY_DIR = DataStorage:getHistoryDir()
+local DOCSETTINGS_DIR = DataStorage:getDocSettingsDir()
 
 local function buildCandidates(list)
     local candidates = {}
@@ -64,120 +65,125 @@ local function buildCandidates(list)
 end
 
 --- Returns path to sidecar directory (`filename.sdr`).
---
 -- Sidecar directory is the file without _last_ suffix.
 -- @string doc_path path to the document (e.g., `/foo/bar.pdf`)
 -- @treturn string path to the sidecar directory (e.g., `/foo/bar.sdr`)
-function DocSettings:getSidecarDir(doc_path)
-    if doc_path == nil or doc_path == '' then return '' end
-    local file_without_suffix = doc_path:match("(.*)%.")
-    if file_without_suffix then
-        return file_without_suffix..".sdr"
+function DocSettings:getSidecarDir(doc_path, force_location)
+    if doc_path == nil or doc_path == "" then return "" end
+    local path = doc_path:match("(.*)%.") or doc_path -- file path without the last suffix
+    local location = force_location or G_reader_settings:readSetting("document_metadata_folder", "doc")
+    if location == "dir" then
+        path = DOCSETTINGS_DIR..path
     end
-    return doc_path..".sdr"
+    return path..".sdr"
 end
 
 --- Returns path to `metadata.lua` file.
 -- @string doc_path path to the document (e.g., `/foo/bar.pdf`)
 -- @treturn string path to `/foo/bar.sdr/metadata.lua` file
-function DocSettings:getSidecarFile(doc_path)
-    if doc_path == nil or doc_path == '' then return '' end
+function DocSettings:getSidecarFile(doc_path, force_location)
+    if doc_path == nil or doc_path == "" then return "" end
     -- If the file does not have a suffix or we are working on a directory, we
     -- should ignore the suffix part in metadata file path.
-    local suffix = doc_path:match(".*%.(.+)")
-    if suffix == nil then
-        suffix = ''
-    end
-    return self:getSidecarDir(doc_path) .. "/metadata." .. suffix .. ".lua"
+    local suffix = doc_path:match(".*%.(.+)") or ""
+    return self:getSidecarDir(doc_path, force_location) .. "/metadata." .. suffix .. ".lua"
 end
 
 --- Returns `true` if there is a `metadata.lua` file.
 -- @string doc_path path to the document (e.g., `/foo/bar.pdf`)
 -- @treturn bool
 function DocSettings:hasSidecarFile(doc_path)
-    return lfs.attributes(self:getSidecarFile(doc_path), "mode") == "file"
+    return lfs.attributes(self:getSidecarFile(doc_path, "doc"), "mode") == "file"
+        or lfs.attributes(self:getSidecarFile(doc_path, "dir"), "mode") == "file"
+        or lfs.attributes(self:getHistoryPath(doc_path), "mode") == "file"
+end
+
+function DocSettings:getLastSaveTime(doc_path) -- for readhistory
+    return lfs.attributes(self:getSidecarFile(doc_path, "doc"), "modification")
+        or lfs.attributes(self:getSidecarFile(doc_path, "dir"), "modification")
 end
 
-function DocSettings:getHistoryPath(fullpath)
-    return HISTORY_DIR .. "/[" .. fullpath:gsub("(.*/)([^/]+)", "%1] %2"):gsub("/", "#") .. ".lua"
+function DocSettings:getHistoryPath(doc_path)
+    if doc_path == nil or doc_path == "" then return "" end
+    return HISTORY_DIR .. "/[" .. doc_path:gsub("(.*/)([^/]+)", "%1] %2"):gsub("/", "#") .. ".lua"
 end
 
 function DocSettings:getPathFromHistory(hist_name)
-    if hist_name == nil or hist_name == '' then return '' end
-    if hist_name:sub(-4) ~= ".lua" then return '' end -- ignore .lua.old backups
+    if hist_name == nil or hist_name == "" then return "" end
+    if hist_name:sub(-4) ~= ".lua" then return "" end -- ignore .lua.old backups
     -- 1. select everything included in brackets
     local s = string.match(hist_name,"%b[]")
-    if s == nil or s == '' then return '' end
+    if s == nil or s == "" then return "" end
     -- 2. crop the bracket-sign from both sides
     -- 3. and finally replace decorative signs '#' to dir-char '/'
     return string.gsub(string.sub(s, 2, -3), "#", "/")
 end
 
 function DocSettings:getNameFromHistory(hist_name)
-    if hist_name == nil or hist_name == '' then return '' end
-    if hist_name:sub(-4) ~= ".lua" then return '' end -- ignore .lua.old backups
+    if hist_name == nil or hist_name == "" then return "" end
+    if hist_name:sub(-4) ~= ".lua" then return "" end -- ignore .lua.old backups
     local s = string.match(hist_name, "%b[]")
-    if s == nil or s == '' then return '' end
+    if s == nil or s == "" then return "" end
     -- at first, search for path length
     -- and return the rest of string without 4 last characters (".lua")
     return string.sub(hist_name, string.len(s)+2, -5)
 end
 
-function DocSettings:getLastSaveTime(doc_path)
-    local attr = lfs.attributes(self:getSidecarFile(doc_path))
-    if attr and attr.mode == "file" then
-        return attr.modification
-    end
-end
-
-function DocSettings:ensureSidecar(sidecar)
-    if lfs.attributes(sidecar, "mode") ~= "directory" then
-        lfs.mkdir(sidecar)
+function DocSettings:getFileFromHistory(hist_name)
+    local path = self:getPathFromHistory(hist_name)
+    if path ~= "" then
+        local name = self:getNameFromHistory(hist_name)
+        if name ~= "" then
+            return ffiutil.joinPath(path, name)
+        end
     end
 end
 
 --- Opens a document's individual settings (font, margin, dictionary, etc.)
--- @string docfile path to the document (e.g., `/foo/bar.pdf`)
+-- @string doc_path path to the document (e.g., `/foo/bar.pdf`)
 -- @treturn DocSettings object
-function DocSettings:open(docfile)
-    --- @todo (zijiehe): Remove history_path, use only sidecar.
-
+function DocSettings:open(doc_path)
     -- NOTE: Beware, our new instance is new, but self is still DocSettings!
     local new = DocSettings:extend{}
-    new.history_file = new:getHistoryPath(docfile)
 
-    local sidecar = new:getSidecarDir(docfile)
-    new.sidecar = sidecar
-    DocSettings:ensureSidecar(sidecar)
-    -- If there is a file which has a same name as the sidecar directory,
-    -- or the file system is read-only, we should not waste time to read it.
-    if lfs.attributes(sidecar, "mode") == "directory" then
-        -- New sidecar file name is metadata.{file last suffix}.lua.
-        -- So we can handle two files with only different suffixes.
-        new.sidecar_file = new:getSidecarFile(docfile)
-        new.legacy_sidecar_file = sidecar.."/"..
-                                  ffiutil.basename(docfile)..".lua"
+    new.doc_sidecar_dir = new:getSidecarDir(doc_path, "doc")
+    new.doc_sidecar_file = new:getSidecarFile(doc_path, "doc")
+    local doc_sidecar_file, legacy_sidecar_file
+    if lfs.attributes(new.doc_sidecar_dir, "mode") == "directory" then
+        doc_sidecar_file = new.doc_sidecar_file
+        legacy_sidecar_file = new.doc_sidecar_dir.."/"..ffiutil.basename(doc_path)..".lua"
+    end
+    new.dir_sidecar_dir = new:getSidecarDir(doc_path, "dir")
+    new.dir_sidecar_file = new:getSidecarFile(doc_path, "dir")
+    local dir_sidecar_file
+    if lfs.attributes(new.dir_sidecar_dir, "mode") == "directory" then
+        dir_sidecar_file = new.dir_sidecar_file
     end
+    local history_file = new:getHistoryPath(doc_path)
 
     -- Candidates list, in order of priority:
     local candidates_list = {
-        -- New sidecar file
-        new.sidecar_file or "",
-        -- Backup file of new sidecar file
-        new.sidecar_file and (new.sidecar_file .. ".old") or "",
+        -- New sidecar file in doc folder
+        doc_sidecar_file or "",
+        -- Backup file of new sidecar file in doc folder
+        doc_sidecar_file and (doc_sidecar_file..".old") or "",
         -- Legacy sidecar file
-        new.legacy_sidecar_file or "",
+        legacy_sidecar_file or "",
+        -- New sidecar file in docsettings folder
+        dir_sidecar_file or "",
+        -- Backup file of new sidecar file in docsettings folder
+        dir_sidecar_file and (dir_sidecar_file..".old") or "",
         -- Legacy history folder
-        new.history_file,
+        history_file,
         -- Backup file in legacy history folder
-        new.history_file .. ".old",
+        history_file..".old",
         -- Legacy kpdfview setting
-        docfile..".kpdfview.lua",
+        doc_path..".kpdfview.lua",
     }
     -- We get back an array of tables for *existing* candidates, sorted MRU first (insertion order breaks ties).
     local candidates = buildCandidates(candidates_list)
 
-    local ok, stored, filepath
+    local ok, stored
     for _, t in ipairs(candidates) do
         local candidate_path = t.path
         -- Ignore empty files
@@ -186,7 +192,6 @@ function DocSettings:open(docfile)
             -- Ignore empty tables
             if ok and next(stored) ~= nil then
                 logger.dbg("DocSettings: data is read from", candidate_path)
-                filepath = candidate_path
                 break
             end
         end
@@ -196,7 +201,6 @@ function DocSettings:open(docfile)
     if ok and stored then
         new.data = stored
         new.candidates = candidates
-        new.filepath = filepath
     else
         new.data = {}
     end
@@ -205,40 +209,33 @@ function DocSettings:open(docfile)
 end
 
 --- Serializes settings and writes them to `metadata.lua`.
-function DocSettings:flush()
-    -- write serialized version of the data table into one of
-    --  i) sidecar directory in the same directory of the document or
-    -- ii) history directory in root directory of KOReader
-    if not self.history_file and not self.sidecar_file then
-        return
-    end
+function DocSettings:flush(data)
+    -- Depending on the settings, doc_settings are saved to the book folder or
+    -- to koreader/docsettings folder. The latter is also a fallback for read-only book storage.
+    local serials = G_reader_settings:readSetting("document_metadata_folder", "doc") == "doc"
+        and { {self.doc_sidecar_dir, self.doc_sidecar_file},
+              {self.dir_sidecar_dir, self.dir_sidecar_file}, }
+         or { {self.dir_sidecar_dir, self.dir_sidecar_file}, }
 
-    -- If we can write to sidecar_file, we do not need to write to history_file anymore.
-    local serials = {}
-    if self.sidecar_file then
-        table.insert(serials, self.sidecar_file)
-    end
-    if self.history_file then
-        table.insert(serials, self.history_file)
-    end
-    self:ensureSidecar(self.sidecar)
-    local s_out = dump(self.data)
-    for _, f in ipairs(serials) do
+    local s_out = dump(data or self.data, nil, true)
+    for _, s in ipairs(serials) do
+        util.makePath(s[1])
+        local sidecar_file = s[2]
         local directory_updated = false
-        if lfs.attributes(f, "mode") == "file" then
+        if lfs.attributes(sidecar_file, "mode") == "file" then
             -- As an additional safety measure (to the ffiutil.fsync* calls used below),
             -- we only backup the file to .old when it has not been modified in the last 60 seconds.
             -- This should ensure in the case the fsync calls are not supported
             -- that the OS may have itself sync'ed that file content in the meantime.
-            local mtime = lfs.attributes(f, "modification")
+            local mtime = lfs.attributes(sidecar_file, "modification")
             if mtime < os.time() - 60 then
-                logger.dbg("DocSettings: Renamed", f, "to", f .. ".old")
-                os.rename(f, f .. ".old")
+                logger.dbg("DocSettings: Renamed", sidecar_file, "to", sidecar_file .. ".old")
+                os.rename(sidecar_file, sidecar_file .. ".old")
                 directory_updated = true -- fsync directory content too below
             end
         end
-        logger.dbg("DocSettings: Writing to", f)
-        local f_out = io.open(f, "w")
+        logger.dbg("DocSettings: Writing to", sidecar_file)
+        local f_out = io.open(sidecar_file, "w")
         if f_out ~= nil then
             f_out:write("-- we can read Lua syntax here!\nreturn ")
             f_out:write(s_out)
@@ -246,77 +243,67 @@ function DocSettings:flush()
             ffiutil.fsyncOpenedFile(f_out) -- force flush to the storage device
             f_out:close()
 
-            if self.candidates ~= nil
-            and G_reader_settings:nilOrFalse("preserve_legacy_docsetting") then
-                for _, t in ipairs(self.candidates) do
-                    local candidate_path = t.path
-                    if candidate_path ~= f and candidate_path ~= f .. ".old" then
-                        logger.dbg("DocSettings: Removed legacy file", candidate_path)
-                        os.remove(candidate_path)
-                        -- We should not remove sidecar folder, as it may
-                        -- contain Kindle history files.
-                    end
-                end
-            end
-
             if directory_updated then
                 -- Ensure the file renaming is flushed to storage device
-                ffiutil.fsyncDirectory(f)
+                ffiutil.fsyncDirectory(sidecar_file)
             end
+
+            self:purge(false, sidecar_file) -- remove old candidates and empty sidecar folders
+
             break
         end
     end
 end
 
-function DocSettings:getFilePath()
-    return self.filepath
-end
-
 --- Purges (removes) sidecar directory.
-function DocSettings:purge(full)
+function DocSettings:purge(full, sidecar_to_keep)
     -- Remove any of the old ones we may consider as candidates in DocSettings:open()
-    if self.history_file then
-        os.remove(self.history_file)
-        os.remove(self.history_file .. ".old")
+    if self.candidates then
+        for _, t in ipairs(self.candidates) do
+            local candidate_path = t.path
+            if lfs.attributes(candidate_path, "mode") == "file" then
+                if (not sidecar_to_keep)
+                        or (candidate_path ~= sidecar_to_keep and candidate_path ~= sidecar_to_keep..".old") then
+                    os.remove(candidate_path)
+                    logger.dbg("DocSettings: purged:", candidate_path)
+                end
+            end
+        end
     end
-    if self.legacy_sidecar_file then
-        os.remove(self.legacy_sidecar_file)
+
+    local function purgeDir(dir, full_purge)
+        if lfs.attributes(dir, "mode") == "directory" then
+            if full_purge then
+                -- Asked to remove all the content of this .sdr directory, whether it's ours or not
+                ffiutil.purgeDir(dir)
+            else
+                -- If the sidecar folder ends up empty, os.remove() can delete it.
+                -- Otherwise, the following statement has no effect.
+                os.remove(dir)
+            end
+        end
     end
-    if lfs.attributes(self.sidecar, "mode") == "directory" then
-        if full then
-            -- Asked to remove all the content of this .sdr directory, whether it's ours or not
-            ffiutil.purgeDir(self.sidecar)
+    purgeDir(self.doc_sidecar_dir, full)
+    purgeDir(self.dir_sidecar_dir, full)
+end
+
+--- Updates sidecar info for file rename/copy/move/delete operations.
+function DocSettings:update(doc_path, new_doc_path, copy)
+    if self:hasSidecarFile(doc_path) then
+        local doc_settings = DocSettings:open(doc_path)
+        if new_doc_path then
+            local new_doc_settings = DocSettings:open(new_doc_path)
+            new_doc_settings:flush(doc_settings.data) -- with current "Book metadata folder" setting
         else
-            -- Only remove the files we know we may have created with our usual names.
-            for f in lfs.dir(self.sidecar) do
-                local fullpath = self.sidecar.."/"..f
-                local to_remove = false
-                if lfs.attributes(fullpath, "mode") == "file" then
-                    -- Currently, we only create a single file in there,
-                    -- named metadata.suffix.lua (ie. metadata.epub.lua),
-                    -- with possibly backups named metadata.epub.lua.old and
-                    -- metadata.epub.lua.old_dom20180528,
-                    -- so all sharing the same base: self.sidecar_file
-                    if util.stringStartsWith(fullpath, self.sidecar_file) then
-                        to_remove = true
-                    end
-                end
-                if to_remove then
-                    os.remove(fullpath)
-                    logger.dbg("DocSettings: purged:", fullpath)
-                end
+            local cache_file_path = doc_settings:readSetting("cache_file_path")
+            if cache_file_path then
+                os.remove(cache_file_path)
             end
-            -- If the sidecar folder ends up empty, os.remove() can delete it.
-            -- Otherwise, the following statement has no effect.
-            os.remove(self.sidecar)
+        end
+        if not copy then
+            doc_settings:purge()
         end
     end
-    -- We should have meet the candidate we used and remove it above.
-    -- But in case we didn't, remove it.
-    if self.filepath and lfs.attributes(self.filepath, "mode") == "file" then
-        os.remove(self.filepath)
-    end
-    self.data = {}
 end
 
 return DocSettings
diff --git a/frontend/readhistory.lua b/frontend/readhistory.lua
index 2b96f65ae..277e3eda3 100644
--- a/frontend/readhistory.lua
+++ b/frontend/readhistory.lua
@@ -146,17 +146,13 @@ function ReadHistory:_readLegacyHistory()
     local history_updated
     local history_dir = DataStorage:getHistoryDir()
     for f in lfs.dir(history_dir) do
-        local path = joinPath(history_dir, f)
-        if lfs.attributes(path, "mode") == "file" then
-            path = DocSettings:getPathFromHistory(f)
-            if path ~= nil and path ~= "" then
-                local file = DocSettings:getNameFromHistory(f)
-                if file ~= nil and file ~= "" then
-                    local item_path = joinPath(path, file)
-                    local item_time = lfs.attributes(joinPath(history_dir, f), "modification")
-                    if self:addItem(item_path, item_time, true) then
-                        history_updated = true
-                    end
+        local legacy_history_file = joinPath(history_dir, f)
+        if lfs.attributes(legacy_history_file, "mode") == "file" then
+            local item_path = DocSettings:getFileFromHistory(f)
+            if item_path then
+                local item_time = lfs.attributes(legacy_history_file, "modification")
+                if self:addItem(item_path, item_time, true) then
+                    history_updated = true
                 end
             end
         end
diff --git a/frontend/ui/elements/common_settings_menu_table.lua b/frontend/ui/elements/common_settings_menu_table.lua
index 94cc25481..3c3d83b5f 100644
--- a/frontend/ui/elements/common_settings_menu_table.lua
+++ b/frontend/ui/elements/common_settings_menu_table.lua
@@ -526,6 +526,34 @@ common_settings.document = {
     -- submenus are filled by menu_order
 }
 
+local metadata_folder_str = {
+    ["doc"] = _("book folder"),
+    ["dir"] = "koreader/docsettings",
+}
+
+local function genMetadataFolderMenuItem(value)
+    return {
+        text = metadata_folder_str[value],
+        checked_func = function()
+            return G_reader_settings:readSetting("document_metadata_folder") == value
+        end,
+        callback = function()
+            G_reader_settings:saveSetting("document_metadata_folder", value)
+        end,
+    }
+end
+
+common_settings.document_metadata_folder = {
+    text_func = function()
+        local value = G_reader_settings:readSetting("document_metadata_folder", "doc")
+        return T(_("Book metadata folder: %1"), metadata_folder_str[value])
+    end,
+    sub_item_table = {
+        genMetadataFolderMenuItem("doc"),
+        genMetadataFolderMenuItem("dir"),
+    },
+}
+
 common_settings.document_auto_save = {
     text_func = function()
         local interval = G_reader_settings:readSetting("auto_save_settings_interval_minutes")
@@ -552,6 +580,7 @@ common_settings.document_auto_save = {
             end,
         } or nil,
     },
+    separator = true,
 }
 
 common_settings.document_save = {
diff --git a/frontend/ui/elements/filemanager_menu_order.lua b/frontend/ui/elements/filemanager_menu_order.lua
index bb83e1fa1..e01b38d24 100644
--- a/frontend/ui/elements/filemanager_menu_order.lua
+++ b/frontend/ui/elements/filemanager_menu_order.lua
@@ -36,6 +36,7 @@ local order = {
         -- end common settings
     },
     document = {
+        "document_metadata_folder",
         "document_auto_save",
         "document_save",
         "document_end_action",
diff --git a/frontend/ui/elements/reader_menu_order.lua b/frontend/ui/elements/reader_menu_order.lua
index 3e1d56712..00054a113 100644
--- a/frontend/ui/elements/reader_menu_order.lua
+++ b/frontend/ui/elements/reader_menu_order.lua
@@ -79,6 +79,7 @@ local order = {
         "status_bar",
     },
     document = {
+        "document_metadata_folder",
         "document_auto_save",
         "document_save",
         "document_end_action",
diff --git a/plugins/exporter.koplugin/clip.lua b/plugins/exporter.koplugin/clip.lua
index 56ee62835..462d95834 100644
--- a/plugins/exporter.koplugin/clip.lua
+++ b/plugins/exporter.koplugin/clip.lua
@@ -1,16 +1,16 @@
+local DataStorage = require("datastorage")
 local DocumentRegistry = require("document/documentregistry")
 local DocSettings = require("docsettings")
-local ReadHistory = require("readhistory")
+local ffiutil = require("ffi/util")
 local lfs = require("libs/libkoreader-lfs")
 local logger = require("logger")
 local md5 = require("ffi/sha2").md5
 local util = require("util")
 local _ = require("gettext")
-local T = require("ffi/util").template
+local T = ffiutil.template
 
 local MyClipping = {
     my_clippings = "/mnt/us/documents/My Clippings.txt",
-    history_dir = "./history",
 }
 
 function MyClipping:new(o)
@@ -333,18 +333,22 @@ end
 
 function MyClipping:parseHistory()
     local clippings = {}
-    for f in lfs.dir(self.history_dir) do
-        self:parseHistoryFile(clippings,
-                              self.history_dir .. "/" .. f,
-                              DocSettings:getPathFromHistory(f) .. "/" ..
-                              DocSettings:getNameFromHistory(f))
+    local history_dir = DataStorage:getHistoryDir()
+    for f in lfs.dir(history_dir) do
+        local legacy_history_file = ffiutil.joinPath(history_dir, f)
+        if lfs.attributes(legacy_history_file, "mode") == "file" then
+            local doc_file = DocSettings:getFileFromHistory(f)
+            if doc_file then
+                self:parseHistoryFile(clippings, legacy_history_file, doc_file)
+            end
+        end
     end
-    for _, item in ipairs(ReadHistory.hist) do
-        self:parseHistoryFile(clippings,
-                              DocSettings:getSidecarFile(item.file),
-                              item.file)
+    for _, item in ipairs(require("readhistory").hist) do
+        if not item.dim then
+            self:parseHistoryFile(clippings, DocSettings:getSidecarFile(item.file, "doc"), item.file)
+            self:parseHistoryFile(clippings, DocSettings:getSidecarFile(item.file, "dir"), item.file)
+        end
     end
-
     return clippings
 end
 
diff --git a/spec/unit/docsettings_spec.lua b/spec/unit/docsettings_spec.lua
index 58df901e5..e76070ff9 100644
--- a/spec/unit/docsettings_spec.lua
+++ b/spec/unit/docsettings_spec.lua
@@ -1,20 +1,38 @@
 describe("docsettings module", function()
-    local docsettings, lfs, util
+    local DataStorage, docsettings, docsettings_dir, ffiutil, lfs
 
     setup(function()
         require("commonrequire")
+        DataStorage = require("datastorage")
         docsettings = require("docsettings")
+        ffiutil = require("ffi/util")
         lfs = require("libs/libkoreader-lfs")
-        util = require("ffi/util")
+
+        docsettings_dir = DataStorage:getDocSettingsDir()
+    end)
+
+    it("should generate sidecar folder path in book folder (by default)", function()
+        G_reader_settings:delSetting("document_metadata_folder")
+        assert.Equals("../../foo.sdr", docsettings:getSidecarDir("../../foo.pdf"))
+        assert.Equals("/foo/bar.sdr", docsettings:getSidecarDir("/foo/bar.pdf"))
+        assert.Equals("baz.sdr", docsettings:getSidecarDir("baz.pdf"))
     end)
 
-    it("should generate sidecar directory path", function()
+    it("should generate sidecar folder path in book folder", function()
+        G_reader_settings:saveSetting("document_metadata_folder", "doc")
         assert.Equals("../../foo.sdr", docsettings:getSidecarDir("../../foo.pdf"))
         assert.Equals("/foo/bar.sdr", docsettings:getSidecarDir("/foo/bar.pdf"))
         assert.Equals("baz.sdr", docsettings:getSidecarDir("baz.pdf"))
     end)
 
-    it("should generate sidecar metadata file", function()
+    it("should generate sidecar folder path in docsettings folder", function()
+        G_reader_settings:saveSetting("document_metadata_folder", "dir")
+        assert.Equals(docsettings_dir.."/foo/bar.sdr", docsettings:getSidecarDir("/foo/bar.pdf"))
+        assert.Equals(docsettings_dir.."baz.sdr", docsettings:getSidecarDir("baz.pdf"))
+    end)
+
+    it("should generate sidecar metadata file (book folder)", function()
+        G_reader_settings:saveSetting("document_metadata_folder", "doc")
         assert.Equals("../../foo.sdr/metadata.pdf.lua",
                       docsettings:getSidecarFile("../../foo.pdf"))
         assert.Equals("/foo/bar.sdr/metadata.pdf.lua",
@@ -23,7 +41,16 @@ describe("docsettings module", function()
                       docsettings:getSidecarFile("baz.epub"))
     end)
 
+    it("should generate sidecar metadata file (docsettings folder)", function()
+        G_reader_settings:saveSetting("document_metadata_folder", "dir")
+        assert.Equals(docsettings_dir.."/foo/bar.sdr/metadata.pdf.lua",
+                      docsettings:getSidecarFile("/foo/bar.pdf"))
+        assert.Equals(docsettings_dir.."baz.sdr/metadata.epub.lua",
+                      docsettings:getSidecarFile("baz.epub"))
+    end)
+
     it("should read legacy history file", function()
+        G_reader_settings:delSetting("document_metadata_folder")
         local file = "file.pdf"
         local d = docsettings:open(file)
         d:saveSetting("a", "b")
@@ -32,15 +59,15 @@ describe("docsettings module", function()
         -- Now the sidecar file should be written.
 
         local legacy_files = {
-            d.history_file,
-            d.sidecar .. "/file.pdf.lua",
+            docsettings:getHistoryPath(file),
+            d.doc_sidecar_dir .. "/file.pdf.lua",
             "file.pdf.kpdfview.lua",
         }
 
-        for _, f in pairs(legacy_files) do
-            assert.False(os.rename(d.sidecar_file, f) == nil)
+        for _, f in ipairs(legacy_files) do
+            assert.False(os.rename(d.doc_sidecar_file, f) == nil)
             d = docsettings:open(file)
-            assert.True(os.remove(d.sidecar_file) == nil)
+            assert.True(os.remove(d.doc_sidecar_file) == nil)
             -- Legacy history files should not be removed before flush has been
             -- called.
             assert.Equals(lfs.attributes(f, "mode"), "file")
@@ -53,7 +80,7 @@ describe("docsettings module", function()
             assert.True(os.remove(f) == nil)
         end
 
-        assert.False(os.remove(d.sidecar_file) == nil)
+        assert.False(os.remove(d.doc_sidecar_file) == nil)
         d:purge()
     end)
 
@@ -62,20 +89,20 @@ describe("docsettings module", function()
         local d = docsettings:open(file)
 
         local legacy_files = {
-            d.history_file,
-            d.sidecar .. "/file.pdf.lua",
+            docsettings:getHistoryPath(file),
+            d.doc_sidecar_dir .. "/file.pdf.lua",
             "file.pdf.kpdfview.lua",
         }
 
         -- docsettings:flush will remove legacy files.
-        for i, v in pairs(legacy_files) do
+        for i, v in ipairs(legacy_files) do
             d:saveSetting("a", i)
             d:flush()
-            assert.False(os.rename(d.sidecar_file, v.."1") == nil)
+            assert.False(os.rename(d.doc_sidecar_file, v.."1") == nil)
         end
 
         d:close()
-        for _, v in pairs(legacy_files) do
+        for _, v in ipairs(legacy_files) do
             assert.False(os.rename(v.."1", v) == nil)
         end
 
@@ -87,45 +114,46 @@ describe("docsettings module", function()
 
     it("should build correct legacy history path", function()
         local file = "/a/b/c--d/c.txt"
-        local history_path = util.basename(docsettings:getHistoryPath(file))
+        local history_path = ffiutil.basename(docsettings:getHistoryPath(file))
         local path_from_history = docsettings:getPathFromHistory(history_path)
         local name_from_history = docsettings:getNameFromHistory(history_path)
         assert.is.same(file, path_from_history .. "/" .. name_from_history)
     end)
 
     it("should reserve last good file", function()
+        G_reader_settings:delSetting("document_metadata_folder")
         local file = "file.pdf"
         local d = docsettings:open(file)
         d:saveSetting("a", "a")
         d:flush()
         -- metadata.pdf.lua should be generated.
-        assert.Equals("file", lfs.attributes(d.sidecar_file, "mode"))
+        assert.Equals("file", lfs.attributes(d.doc_sidecar_file, "mode"))
         d:flush()
         -- metadata.pdf.lua.old should not yet be generated.
-        assert.are.not_equal("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+        assert.are.not_equal("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
         -- make metadata.pdf.lua older to bypass 60s age needed for .old rotation
         local minutes_ago = os.time() - 120
-        lfs.touch(d.sidecar_file, minutes_ago)
+        lfs.touch(d.doc_sidecar_file, minutes_ago)
         d:close()
         -- metadata.pdf.lua and metadata.pdf.lua.old should be generated.
-        assert.Equals("file", lfs.attributes(d.sidecar_file, "mode"))
-        assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+        assert.Equals("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+        assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
 
         -- write some garbage to sidecar-file.
-        local f_out = io.open(d.sidecar_file, "w")
+        local f_out = io.open(d.doc_sidecar_file, "w")
         f_out:write("bla bla bla")
         f_out:close()
 
         d = docsettings:open(file)
         -- metadata.pdf.lua should be removed.
-        assert.are.not_equal("file", lfs.attributes(d.sidecar_file, "mode"))
-        assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+        assert.are.not_equal("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+        assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
         assert.Equals("a", d:readSetting("a"))
         d:saveSetting("a", "b")
         d:close()
         -- metadata.pdf.lua should be generated.
-        assert.Equals("file", lfs.attributes(d.sidecar_file, "mode"))
-        assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+        assert.Equals("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+        assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
         -- The contents in sidecar_file and sidecar_file.old are different.
         -- a:b v.s. a:a
 
@@ -133,87 +161,89 @@ describe("docsettings module", function()
         -- The content should come from sidecar_file.
         assert.Equals("b", d:readSetting("a"))
         -- write some garbage to sidecar-file.
-        f_out = io.open(d.sidecar_file, "w")
+        f_out = io.open(d.doc_sidecar_file, "w")
         f_out:write("bla bla bla")
         f_out:close()
 
         -- do not flush the result, open docsettings again.
         d = docsettings:open(file)
         -- metadata.pdf.lua should be removed.
-        assert.are.not_equal("file", lfs.attributes(d.sidecar_file, "mode"))
-        assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+        assert.are.not_equal("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+        assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
         -- The content should come from sidecar_file.old.
         assert.Equals("a", d:readSetting("a"))
         d:close()
         -- metadata.pdf.lua should be generated.
-        assert.Equals("file", lfs.attributes(d.sidecar_file, "mode"))
-        assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+        assert.Equals("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+        assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
     end)
 
     describe("ignore empty sidecar file", function()
         it("should ignore empty file", function()
+            G_reader_settings:delSetting("document_metadata_folder")
             local file = "file.pdf"
             local d = docsettings:open(file)
             d:saveSetting("a", "a")
             d:flush()
             -- metadata.pdf.lua should be generated.
-            assert.Equals("file", lfs.attributes(d.sidecar_file, "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file, "mode"))
             -- make metadata.pdf.lua older to bypass 60s age needed for .old rotation
             local minutes_ago = os.time() - 120
-            lfs.touch(d.sidecar_file, minutes_ago)
+            lfs.touch(d.doc_sidecar_file, minutes_ago)
             d:close()
             -- metadata.pdf.lua and metadata.pdf.lua.old should be generated.
-            assert.Equals("file", lfs.attributes(d.sidecar_file, "mode"))
-            assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
 
             -- reset the sidecar_file to an empty file.
-            local f_out = io.open(d.sidecar_file, "w")
+            local f_out = io.open(d.doc_sidecar_file, "w")
             f_out:close()
 
             d = docsettings:open(file)
             -- metadata.pdf.lua should be removed.
-            assert.are.not_equal("file", lfs.attributes(d.sidecar_file, "mode"))
-            assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+            assert.are.not_equal("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
             assert.Equals("a", d:readSetting("a"))
             d:saveSetting("a", "b")
             d:close()
             -- metadata.pdf.lua should be generated.
-            assert.Equals("file", lfs.attributes(d.sidecar_file, "mode"))
-            assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
             -- The contents in sidecar_file and sidecar_file.old are different.
             -- a:b v.s. a:a
         end)
 
         it("should ignore empty table", function()
+            G_reader_settings:delSetting("document_metadata_folder")
             local file = "file.pdf"
             local d = docsettings:open(file)
             d:saveSetting("a", "a")
             d:flush()
             -- metadata.pdf.lua should be generated.
-            assert.Equals("file", lfs.attributes(d.sidecar_file, "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file, "mode"))
             -- make metadata.pdf.lua older to bypass 60s age needed for .old rotation
             local minutes_ago = os.time() - 120
-            lfs.touch(d.sidecar_file, minutes_ago)
+            lfs.touch(d.doc_sidecar_file, minutes_ago)
             d:close()
             -- metadata.pdf.lua and metadata.pdf.lua.old should be generated.
-            assert.Equals("file", lfs.attributes(d.sidecar_file, "mode"))
-            assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
 
             -- reset the sidecar_file to an empty file.
-            local f_out = io.open(d.sidecar_file, "w")
+            local f_out = io.open(d.doc_sidecar_file, "w")
             f_out:write("{                               }                 ")
             f_out:close()
 
             d = docsettings:open(file)
             -- metadata.pdf.lua should be removed.
-            assert.are.not_equal("file", lfs.attributes(d.sidecar_file, "mode"))
-            assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+            assert.are.not_equal("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
             assert.Equals("a", d:readSetting("a"))
             d:saveSetting("a", "b")
             d:close()
             -- metadata.pdf.lua should be generated.
-            assert.Equals("file", lfs.attributes(d.sidecar_file, "mode"))
-            assert.Equals("file", lfs.attributes(d.sidecar_file .. ".old", "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file, "mode"))
+            assert.Equals("file", lfs.attributes(d.doc_sidecar_file .. ".old", "mode"))
             -- The contents in sidecar_file and sidecar_file.old are different.
             -- a:b v.s. a:a
         end)