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SAP on SLES with BtrFS

markus_doehr2
Active Contributor
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Hi all,

is someone using SLES system with BtrFS (either / or database or both)? I'd like to hear (and share) experiences.

Regards,

Markus

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fabian_herschel
Advisor
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With SLES12 btrfs is the default file system for /. This is part of the idea to get a rollback functionality for the *system*, for example after a failed system update.

The following tutorial session from SUSECon2014 explains a bit the ideas, concepts, requirements and limits. It's about "myth and truth".

http://www.susecon.com/doc/2014/sessions/TUT5802.pdf

Hope that helps a bit to differ between the SLES11 (SP3) and SLES12  feature set.

markus_doehr2
Active Contributor
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Hi Fabian,

thank you for sharing.

I know that and snapshot functionality is just what I planned to use (pre-downtime on upgrades etc.) instead of storage system snapshots.

Unfortunately seven (7) systems crashed with various BtrFS related filesystem errors in the last five months, we even had data los on two (smaller) systems because the log and log mirror filesystem was hosed (on BtrFS).

One system had a root filesystem with LVM and BtrFS and was "full", rebalancing didn't work because there was allegedly "no space available", so eventually we also had to restore that system from a backup (that one was on SLES12). The SuSE support could also not help us.

It may work, our experiences just show it's not really stable, neither for root nor for application or database data, hence we migrated all our instances (60+) away from BtrFS and use ext3 and xfs now.

--

Markus

fabian_herschel
Advisor
Advisor
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I hope you informed SUSE support about your migration from BtrFS to ext3, so they could communicate your bad experiences with the developement. Internally I try a research on this issue.
If interested, please send me a direct eMail, because I could not see your contact data here in SCN. Could be needed that I know your company name to reference your issue.

markus_doehr2
Active Contributor
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Hi Fabian,

yes, there are a few SR's open with SuSE, we got a kernel who should help in finding out the problem but since we migrated all systems away already in the last weeks (I literally had no weekend in 2 months) we don't have a system on BtrFS any more and hence we can't implement the kernel to see if it helps narrowing down the original issue.

Our SAP customer no. is 36620, if that may help. You can also check the Novell SRs 10954983661 and 10964582722.

Another problem with BtrFS as root filesystem is the fact, that a DB2 installation expects a real "filesystem" for /tmp and not a submount. An OSS call (560294/2015) stated, that BtrFS as /tmp submount for DB2 installation is not supported.

Regards,

Markus