Cluster size modification doesn't work for exFAT

[Paul]

Hello,

When I create a container file with exFAT file system I noticed that the modification of the cluster size doesn't work. Indeed, when the container is created, the cluster size is always the default value according to the size of the container (my parameter is not taken into account):
< 256 Mo : 4ko
256 Mo - 32 Go : 32 ko
32 Go - 256 To : 128 ko
...
I performed the test with NTFS format and it's work well. I can corretly change the cluster size, this one is well taken into account when the container is created.
Does anyone know why it doesn't work with exFAT format?

Thanks!

(I used VeraCrypt 1.21 under W7)

[wesh94]

Hello,

I have the same problem, it is not possible to modify the cluster size with exfat, it's always the default size.
Do you have a solution ?

i use veracrypt 1.23 hotfix 2 under w10

[Adrian Kentleton]

I cannot reproduce this issue on Win7 32-bit, VC 1.23. A 299MB test volume can be successfully created with 4KB cluster size.

How do you determine the cluster size of your exFAT volumes?

[wesh94]

On your 299MB volume, when you write a file smaller than 32KB, the size on the disk will be 32KB

[Adrian Kentleton]

And if you write a second file smaller than 32KB, what do you get?

[wesh94]

The cluster size is 32k

For a volume >32go, the cluster size is 128k

[Adrian Kentleton]

My test results:

Create a 1KB file:

I wonder if the problem is, that you are creating an exFat volume on a drive, the underlying file system of which has 32KB clusters? The underlying file system of my drive, formatted NTFS, has 4KB clusters:

[wesh94]

No, the drive is ntfs 4KB.
I tested on 4 different pc and always the same problem
windows 10 64bit, windows 7 32bit, windows 7 34bit

[Adrian Kentleton]

Very odd! I have now been able to reproduce the issue, running a test on W10 Home 64-bit, VC 1.23. C: drive formatted NTFS, chkdsk reports 4 KB clusters; 500MB VC volume, exFAT set at 4KB, but chkdsk reports 32KB clusters.

I also re-ran the test on my W7 Home 32-bit PC, creating the volume on the OS system C: drive (4KB clusters), in case that might be relevant, but I got the 4KB exFAT clusters, as before.

Will do some further tests tomorrow, on W8 Home 64-bit, and W7 & W10 Pro 32-bit PCs.

Can't think of any good reason why this happens.

[Adrian Kentleton]

More tests; all underlying drives formatted NTFS 4KB clusters, test 500MB volume, exFAT 4KB, chkdsk reports:

Win 8 Home 64-bit: exFAT 32KB clusters

Win 7 Pro 32-bit: exFAT 4KB clusters
Win 10 Pro 32-bit: exFAT 32KB clusters

The two Pro OSs are on a dual-boot PC, and the (different) test volumes were created on the same (non-system) common partition!

[Jeff M]

This issue still appears to exist, and I have tried from WIndows 10, OSX10.12 and 10.15, and Ubuntu 18.04. I seem to be unable to specify the cluster size when creating a veracrypt partition using the exFAT file system. Instead of starting a new post on this I figured I'd start here. Is there some way to accomplish this that I'm missing? Or is this a known bug/limitation/issue? If so, is there an open documented request to address it?

[Barrett Booth]

Has anyone been able to figure this out? Is there a way to contact the developers for Veracrypt and get direct feedback on this?

[Mounir IDRASSI]

@adriankit , @jeffm333, @bbworks : this issue has been normally fixed in 1.24-Update7 on Windows through the use of the native Windows format program. Here is the entry in the 1.24-Update7 version history:

• Use native Windows format program to perform formatting of volume since it is more reliable and only fallback to FormatEx function from fmifs.dll in case of issue.

Does anyone reproduce the issue on Windows with 1.24-Update7? On my side, I can't reproduce it on latest Windows 10 64-bit.

For Linux and macOS, it is a different story: VeraCrypt doesn't allow setting a custom cluster size. So, the default value defined by the OS will be used. An enhancement would be add such option in VeraCrypt UI or command line and then invoke the OS helper to perform exFAT formatting using the given cluster size.
For example, under Linux, mkfs.exfat accepts the switch "-s sectors-per-cluster" so we can display a droplist with value that depend on sector size (e.g if sector size is 4K, then smallest cluster size will be 4K).

[NesteaZen]

why doesn't my filesystem info show?
I'm on windows 10, 10.0.19041.867 Public release: March 9, 2021
using vc portable. Do I need install in order for this to work?