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btrfs-cleaner frequently stuck at 100% CPU after 6.4.0 upgrade
Since I upgraded my RN102 to 6.4.0 last night I frequently have trouble reaching the admin interface, and my laptop has reported not being able to reach Time Machine. When I login by ssh and use ...
It seems like I found a way to get rid of the hanging btrfs-cleaner: After switching off quota
btrfs quota disable /data
btrfs-cleaner did never show up again (in top).
(After booting I usualy had about a minute to issue the command before btrfs-cleaner did spawn and prevented the command to respond.)
I did not intentionally enable quota - i guess it was enabled by default.
Good luck,
HansW
PS: Maybe the problem is known by Netgear - in their "FAQs on recently released firmware 6.4.0" (see link on top of page) they talk about "... this is likely due to the ReadyNAS performing a quota check".
Some websites also describe problems with quota and btrfs (Rockstor forum), other sites cite the quota support in btrfs as experimental (but these might be out of date).
I did not extensive testing after diabling quota that way - I'm happy that I can acces my files again ...
HansWeihnacht You sir, are a legend.
For the first time in 2 weeks, something of use to my conundrum...
Found btrfs-cleaner running at 97% CPU usage and disabled the quota as per your post.
The process stopped, and slowly things seem to have normalised - LAN access, web interface etc.
I also noticed the data usage as "Free" and "Snapshots" - this worries me, because if quota somehow becomes enabled again and it sees the data volume as snapshots, who knows what it may do?
As it stands I am going to run with this for now, and hope that Netgear release a patch for all of this mess soon, so that we don't have to dabble around in SSH to blindly try fix issues which should not be present in a final firmware release...
Thank you again!
Quotas are used to determine how much space is used by snapshots. The system does not need quotas to know what is a snapshot and what isn't.
If you haven't been running volume maintenance I would suggest you run it and once it is complete turn quotas back on.
As you have seen some code is not designed to handle btrfs quota being disabled as we don't support doing that.
Couple things to consider,
1. If you do not care about share quotas you can leave it disabled, if you care about the metrics you can reenable them and qgroups will begin rescanning and correcting the metrics in the interface.
2. Please, Please, Please, while you have the resources on your systems run the Scheduled Maintenance. This will benefit the FS in the future.
Alex
An issue has been identified that may explain the slowdown.
So I would probably leave quotas disabled for now (if you have disabled them) and then provide feedback if the next beta build (once available) resolves the problem.
If you have disabled quotas please try to avoid adding shares or changing the quota setting on existing shares.Hi,
I have this problem on a 316 with 3x6TB drives. Every once in awhile the shares and admin panel are inaccessible and when I SSH to the machine I can see btrfs-cleaner pegged near 100%. I renice'd the process to a niceness of 10, but it doesn't really seem to help.
The thing is, I don't have any quotas enabled at all. I just have a handful of shares and some of them have the hourly snapshot feature turned on. This seems to be in relation to cleaning up snapshots?
I'm not adding or deleting many files. One snapshotted subvolume (share) is about 6TB in total, but changes very little, maybe 30-50GB a week.
Damon
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