Stratis Storage support

[timwhite1]

Stratis Storage relies on LVM / DM-Tables thin volumes as well. I'm very encouraged by your project and its capabilities. Has anyone tested this on a Stratis Storage Pool? I cannot see why it wouldn't work.

[tasket]

It would be interesting to see if that worked. Assuming the thin-provisioning-tools commands like thin_delta can't be used directly on Stratis objects, what would be the analog to use under Stratis?

BTW in a bit of an ironic twist, Wyng is adding support for reflink image files on Btrfs and XFS. IIRC Stratis uses XFS on top of its thin block layer.

(As for relative merits, someday I'd love to see an apples-to-apples benchmark comparison of COW storage systems, including Ext4-on-dm-thin, Stratis and Btrfs.)

[tlaurion]

@timwhite1 ?

[timwhite1]

It would be interesting to see if that worked. Assuming the thin-provisioning-tools commands like thin_delta can't be used directly on Stratis objects, what would be the analog to use under Stratis?

Not sure if this is a great answer but here is my understanding of how it works--

Command syntax is:
stratis filesystem snapshot <pool_name> <file_system_name> <snapshot_name>

That creates a thin snapshot of the entire XFS file system via underlying DM-thin mechanisms. More info here:
stratis-storage/project#541 (reply in thread)

Per this Redhat KB as "thin" as it might be "Each snapshot uses around half a gigabyte of actual backing storage, which is needed for the XFS log." That seems outlandish.
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/managing_file_systems/using-snapshots-on-stratis-file-systems_managing-file-systems

BTW in a bit of an ironic twist, Wyng is adding support for reflink image files on Btrfs and XFS. IIRC Stratis uses XFS on top of its thin block layer.

Yes a Stratis Filesystem is XFS. In some not so great news I've learned that Stratis COW functionality is limited to when you manually run a CP or other iotcl command. But more typical writes will be overwrites, not COW. This is disappointing and not really what one would expect of a system calling itself "copy on write". More info here (same thread as above):
stratis-storage/project#541 (reply in thread)

(As for relative merits, someday I'd love to see an apples-to-apples benchmark comparison of COW storage systems, including Ext4-on-dm-thin, Stratis and Btrfs.)

Agreed! And someday before long we should have bcachefs joining the ranks. Would love to see some comparison as well!