REFS performance issue "workaround"

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Re: REFS performance issue "workaround"

Veeam Logoby dellock6 » Tue Jul 11, 2017 11:23 am 1 person likes this post

I believe the biggest benefit here is the monthly active full , which completely breaks the chain and restart a fresh one without involving too many deletions and transforms, which we have all understood by new are the most serious candidates to be the root problem. I don't see per-vm to be an issue to be honest.
Luca Dell'Oca
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Re: REFS performance issue "workaround"

Veeam Logoby mkretzer » Tue Jul 11, 2017 4:17 pm

We did an experiment: We have a volume where fast clone has got really slow. Fast clone for one specific job took 6 hours instead of ~25 minutes it took in the first few weeks. Now after an active full fast clone two days after the active full (it only had to merge 2 backup points!) took 4 1/2 hours. So in our case active full did not help at all!
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Re: REFS performance issue "workaround"

Veeam Logoby DaStivi » Tue Jul 11, 2017 9:10 pm

hello
does anyone here having strange CPU issues with refs?
i noticed now a couple of times, that after a backup, when veeam starts to delete old vib files (perVM Backup) the backup repo server starts using all 8vCPUs and than locks up completly... no login is possible... right now i've restarted it a couple of times and after a few minutes the same behavoir started... i've removed the refs disks from my vm now and the server boots normally and i can login and right now i'm installing the latest windows cumulative updates...

btw. i'm on build 14393.1358 (and as far as i understand the "old" fixes should be in there allready: post247790.html#p247790)

i checked last syn full run of this backup repository, i sadly i've to notice the very long "fast clone" too, as it took 2h20min.. :shock:
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Re: REFS performance issue "workaround"

Veeam Logoby kubimike » Tue Jul 11, 2017 11:16 pm

@DaStivi same issue I had, contact Veeam open a case get the beta refs driver. In this case it fixed it for me.
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Re: REFS performance issue "workaround"

Veeam Logoby kubimike » Wed Jul 12, 2017 2:35 pm

my fastclones are now taking 3 hours after fixing the retention issue. I am going through my backups before July 4th and it only took roughly an hour. Now it takes over 3 hours to make one.
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Re: REFS performance issue "workaround"

Veeam Logoby mkretzer » Thu Jul 13, 2017 3:58 am

The worst thing is; fast clones will continue to get slower and will never recover unless you reformat (or perhaps delete all the data). Thats why i had this idea for an workaround in this thread.
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