Large files are split when browsed in Explorer due to FAT32 emulation?


Large files are split when browsed in Explorer due to FAT32 emulation?...
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jphughan
jphughan
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I've just noticed that when I mount a File and Folder Backup in Explorer, the virtual disk appears as FAT32, even though all data it contains was backed up from a single NTFS volume. I wondered what the implications might be on files that were larger than 4GB, and sure enough when I browsed to a file that I knew was larger on the source disk, on this virtual disk it had been split up into several files. I assume that if I used Reflect to perform a restore, large files would be restored properly, but is there no way to have Reflect emulate another file system that supports large files natively so that they can be restored via simple copy/paste from a mounted image? Even if NTFS emulation is complicated with these backups, could they perhaps be mounted as exFAT when Reflect is running on an OS that supports that file system, which is Vista/Server 2008 SP1 onward? FAT32 emulation could of course be kept as a legacy emulation mode for anyone still on XP/Server 2003.

Also, this FAT32 emulation also makes me wonder why the "Enable access to restricted folders" checkbox even exists for mounting File and Folder backups given that FAT32 has no ACLs.
Edited 29 March 2017 3:12 AM by jphughan
jphughan
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Bumping this topic

Nick
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Hi 

Thanks for posting

Yes, it's necessary to use the 'File and Folder' restore option in Macrium Reflect to restore files larger than 4GB as Windows doesn't recognise the extensions we use for large files. Using the File and FolderRestore option will also restore NTFS ACLs in the backups

http://knowledgebase.macrium.com/display/KNOW7/Restoring+a+file+and+folder+backup

Reverse engineering exFAT for the backup file layout is a complex option but was considered in the past.  We have a backlog item to either use UDF or provide our own extension to FAT32 for large files when mounting File and Folder backup files.

You are correct in that the 'Enable Access to Restricted Folders' option has no affect when mounting File and Folder backups. 




Kind Regards

Nick - Macrium Support

Edited 30 March 2017 12:31 AM by Nick
jphughan
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Thanks Nick!  I've updated the how-to documentation I prepare for my client to call this limitation out at least for the time being.

jphughan
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Bumping this.  I'm reading that the maximum possible partition size for FAT32 is 2TB.  Assuming this is accurate, would Reflect have the same limitation or does it have a way around this?  If Reflect is subject to this limit, what would happen if the total amount of data in an F&F backup exceeded that?  Would I not be able to mount the backup as a virtual disk but still be able to restore in Reflect, or would I not be able to create an F&F backup that large in the first place?

Edited 27 May 2017 3:31 AM by jphughan
Nick
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Hi 

Thanks for posting

 I'm reading that the maximum possible partition size for FAT32 is 2TB

You've possibly read "The boot sector uses a 32-bit field for the sector count, limiting the FAT32 volume size to 2 TiB" in Wikipedia.

https://en.wikipedia.org/wiki/File_Allocation_Table

This isn't strictly correct as the BIOS Parameter Block (BPB) sector count field isn't a restraint on mounting the file system unless the file system is mounted using the disk partition table. File and Folder backups are mounted directly and Reflect uses 256KB file system clusters which has a maximum mounted volume size of 2**28 * 256 * 1024 = 64TB .  While I don't have a 64TB File and Folder backup to demonstrate, below are some screen shots of File and Folder mounted FAT 32 file systems > 2 TB to put your mind at rest:

2.6 TB:
http://forum.macrium.com/uploads/images/627840f7-b4d6-4ad9-8248-8b1a.png

The type of the file system is FAT32.
Volume Serial Number is 592A-B793
Windows is verifying files and folders...
File and folder verification is complete.

Windows has scanned the file system and found no problems.
No further action is required.
2,791,485,952 KB total disk space.
430,878,464 KB in 137 hidden files.
   93,184 KB in 364 folders.
1,895,267,840 KB in 721 files.
465,246,208 KB are available.

  262,144 bytes in each allocation unit.
 10,904,242 total allocation units on disk.
  1,817,368 allocation units available on disk.


5.1 TB:
http://forum.macrium.com/uploads/images/a5c9347e-b0b7-4c8d-b4a8-5c57.png


Kind Regards

Nick - Macrium Support

Richard V.
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Does that mean I'm out of luck if I want to create a File and Folder backup larger than 64 TB?  Seagate assures me that I can get up to 1 PB with "only" 17 of these.  So Macrium had better catch up soon. Laugh

Regards, Richard V. ("Arvy")
https://forum.macrium.com/uploads/images/afc5d4fe-5d25-4e25-be94-185e.png

Edited 28 May 2017 3:32 PM by Arvy
jphughan
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Awesome, thanks Nick!!
Lars
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jphughan - 28 May 2017 3:59 PM
Awesome, thanks Nick!!

My vote is go UDF.

Smile


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