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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with quota and btrfs (Rockstor forum), other sites cite the quota support in btrfs as experimental (but these might be out of date).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 ...
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with quota and btrfs (Rockstor forum), other sites cite the quota support in btrfs as experimental (but these might be out of date).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 wrote:It seems like I found a way to get rid of the hanging btrfs-cleaner: After switching off quota
btrfs quota disable /data
Thanks a lot Hans, this sounds like the first sensible, workable solution in this thread. I don't have access to my NAS until November, but this is the first thing I'll try when I do.
Joachim
I have no idea what side-effects it may bring - I'm not too deep into the details of BTRFS.
What I noticed so far:
* Read- and write-acces as before
* Snapshot creation and deletion works as before (according to ReadyNAS-Logs)
* btrfs-cleaner never used noticeable CPU since (logging in intervals of 15min)
* ReadyNAS Admin-Page shows data-usage only "Snapshots" and "Free" (no "Data" any more, but I'm not sure wheter that's related to switching off quota - might be, because tha data on disk tends to be "old")
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!
HansWeihnacht wrote: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).
Hi Hans,
like you, I haven't enabled quota myself and they're not used in any of my shares.
I would've tried the "quota disable" command if it had been obvious whether it destroys all of the qgroups on the volume (visible using "qgroup show /data"). Is this documented anywhere for btrfs?
It's also not clear how to re-enable quota if it requires re-creating all the qgroups as described on the wiki. Is it documented anywhere how ReadyNAS OS requires qgroups to be set up?
In the end, by the time I got access to my NAS 6.4.1-T21 beta was out, so I installed it and haven't had problems since (after 10h of uptime, btrfs-cleaner is still below 7s of CPU time). So I'll consider this fixed if the beta ever turns into a release.
Cheers,
joki
I see a similar issue, but not matching the descriptions exactly. In my case, top doesn't show btrfs-cleaner using 100% CPU, but if I install iotop, I see the process eating all of the available disk IO, meaning that most of the CPU is spent in iowait. This causes any other disk-bound process to run extremely slowly; I see similar usability symptoms as others (slow FrontView response, failed NAS mounting, file reads, etc).
This has been persistent under 6.4.0 and the latest 6.4.1 RC3 (running RC3 and observing this as I type):
Total DISK READ: 759.25 K/s | Total DISK WRITE: 0.00 B/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND 1938 be/4 root 381.48 K/s 503.70 K/s 0.00 % 97.83 % [btrfs-cleaner] 1939 be/4 root 374.07 K/s 500.00 K/s 0.00 % 96.80 % [btrfs-transacti]
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