[Windows Mobile Apps and Games] RoryB:
Read my boot.rgu file. Here is the cache parts

[HKEY_LOCAL_MACHINE\System\StorageManager\Filters\fsreplxfilt]
"ReplStoreHostVolume"=""
"ReplStorePath"="[URL="file://\\ReplStorVol"]\\ReplStorVol[/URL]"
"ReplStoreName"="ReplStor"
"ReplStoreDoImmaculate"=dword:0
"ReplStoreCacheSize"=dword:0
"NumDirsToExclude"=dword:0
"DirsToExclude"=multi_sz:""
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
[HKEY_LOCAL_MACHINE\System\StorageManager\FATFS]
"FriendlyName"="FAT FileSystem"
"Dll"="fatfsd.dll"
"Flags"=dword:00000064
"Paging"=dword:1
"EnableCache"=dword:1
"CacheSize"=dword:0
"Util"="fatutil.dll"
"CacheDll"="diskcache.dll"
[HKEY_LOCAL_MACHINE\System\StorageManager\FATFS]
"Flags"=dword:00000024
;;; Trials that did not seem to do anything
;;; "CacheSize"=dword:1024
;;; "CacheSize"=dword:4096
[HKEY_LOCAL_MACHINE\System\StorageManager\FATFS\Filters\CacheFilt]
"Dll"="CacheFilt.dll"
"Order"=dword:12
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\TRUEFFS_DOC1]
"DefaultFileSystem"="FATFS"
"Name"=""
"PartitionDriver"=""
"Folder"="Extended_ROM"
"MountHidden"=dword:1
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\TRUEFFS_DOC1\FATFS]
"Flags"=dword:14
"FormatTfat"=dword:1
"EnableWriteBack"=dword:1
"DataCacheSize"=dword:00000080 ;128 sectors(128*512=64KB)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\TRUEFFS_DOC2]
"DefaultFileSystem"="FATFS"
"Name"=""
"PartitionDriver"=""
"Folder"=""
"MountFlags"=dword:6
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\TRUEFFS_DOC2\FATFS]
"Flags"=dword:00600014
"FormatTFAT"=dword:1
"CheckForFormat"=dword:1
"MountAsBootable"=dword:1
"MountAsRoot"=dword:1
"EnableWriteBack"=dword:1
"DataCacheSize"=dword:00000080

So for now I should change to be

[HKEY_LOCAL_MACHINE\System\StorageManager\Filters\fsreplxfilt]
"ReplStoreHostVolume"=""
"ReplStorePath"="[URL="file://\\ReplStorVol"]\\ReplStorVol[/URL]"
"ReplStoreName"="ReplStor"
"ReplStoreDoImmaculate"=dword:0
"ReplStoreCacheSize"=dword:0
"NumDirsToExclude"=dword:0
"DirsToExclude"=multi_sz:""
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
[HKEY_LOCAL_MACHINE\System\StorageManager\FATFS]
"FriendlyName"="FAT FileSystem"
"Dll"="fatfsd.dll"
"Flags"=dword:00000064
"Paging"=dword:1
"EnableCache"=dword:1
[COLOR=red]"DataCacheSize"=dword:0[/COLOR]
[COLOR=red]"FatCacheSize"=dword:0[/COLOR]
"Util"="fatutil.dll"
"CacheDll"="diskcache.dll"
[HKEY_LOCAL_MACHINE\System\StorageManager\FATFS]
"Flags"=dword:00000024
[HKEY_LOCAL_MACHINE\System\StorageManager\FATFS\Filters\CacheFilt]
"Dll"="CacheFilt.dll"
"Order"=dword:12
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\TRUEFFS_DOC1]
"DefaultFileSystem"="FATFS"
"Name"=""
"PartitionDriver"=""
"Folder"="Extended_ROM"
"MountHidden"=dword:1
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\TRUEFFS_DOC1\FATFS]
"Flags"=dword:14
"FormatTfat"=dword:1
"EnableWriteBack"=dword:1
[COLOR=red];;;[/COLOR] "DataCacheSize"=dword:00000080 ;128 sectors(128*512=64KB)
[COLOR=red][COLOR=red]"DataCacheSize"=dword:1000[/COLOR]
"FatCacheSize"=dword:100[/COLOR]
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\TRUEFFS_DOC2]
"DefaultFileSystem"="FATFS"
"Name"=""
"PartitionDriver"=""
"Folder"=""
"MountFlags"=dword:6
[HKEY_LOCAL_MACHINE\System\StorageManager\Profiles\TRUEFFS_DOC2\FATFS]
"Flags"=dword:00600014
"FormatTFAT"=dword:1
"CheckForFormat"=dword:1
"MountAsBootable"=dword:1
"MountAsRoot"=dword:1
"EnableWriteBack"=dword:1
[COLOR=red];;;[/COLOR] "DataCacheSize"=dword:00000080
[COLOR=red][COLOR=red]"DataCacheSize"=dword:1000[/COLOR]
"FatCacheSize"=dword:100[/COLOR]

and then later after cache is added to Extendir try changing [HKEY_LOCAL_MACHINE\System\StorageManager\FATFS] "EnableCache"=dword:1 to be "EnableCache"=dword:0

Do I understand correctly?

I am getting ready to test Extendir v2 Beta 1.03

BTW I read some of this when I was trying to figure out how to get Extended_ROM as a file space, but it did not sink in that I should look at changing these other filters.