ReFS & fast Cloning - performance of Reverse Incremental

[qmonteyne]

Hi everyone,

I'm looking to see if anyone could share any benchmarks of Reverse Incrementals on a medium infra (+-15TB), using Per-VM chains on ReFS / 2016 repo, vs. regular incrementals w/ weekly synthetic fulls.

is there still a performance impact to be reckoned with, given the fast clone ability, versus 'regular' Incrementals?
is the I/O assertion still correct, given the fast clone (3 I/O for Reverse Incremental, 1R+2W) ?

What's the currently accepted best practice?

the articles I know of haven't been updated to reflect ReFS / Fast Cloning yet example here https://bp.veeam.expert/job_configurati ... thods.html

Thanks,
Q.

[Gostev]

Hi, Quentin. Fast cloning accelerates all backup modes that include full backup file transformation, but the best practice is not to use reverse incremental with ReFS due to the backup mode causing additional fragmentation... there's an existing discussion with more details on why this happens if you want more details. Thanks!

[qmonteyne]

Hi Gostev,

thanks for your reply. According to your recommendation, we won't be doing reverse incrementals.
If you can easily point me to the existing discussion you're referring to, I'd love to read it.

But I can't get the Fast Clone to work on this job
it's probably because the repository was first created in NTFS and subsequently formatted in ReFS, but it's definitely well-recognized now ("align blocks" greyed out).
No existing ntfs-made backups were left, I created a chain from scratch expecting it would fast-clone.
When it didn't, I performed a Compact, no avail.
Now it's just ran its first Synth Full, and well ... it took over 30 hours (12TB) and no sign of fast cloning in the logs.

Where can I look and can I do anything except start from scratch (delete repo, start new chain)? I'll open a tech case later today.

thx,
Quentin

PS and totally unrelated: I'm not a twitter hero so I hope you got my message about Nine Email for Android

[qmonteyne]

think I found it .... I recreated the volumes underlying to the repositories, but not the repositories themselves.
when going back in the settings on ReFS, the "align" was greyed out tricking me to think Veeam had figured it out, but it was greyed-out unchecked
Now i've recreated the repo's (which now have the align option greyed out checked), removed the old backups from config, rescanned the newly-made repo's, and am following through with Active Fulls.

We'll know tonight or tomorrow but I think i've got it now. Will report back for future reference.