Re: Bad fs performance, IO freezes

[Donald Pearson <donaldwhpearson@gmail.com>]

I get the same kind of muddy errors when I do a quota rescan on the
filesystem or qgroup show on any subvolume on mine, and I know I don't
have them enabled.

On Mon, Oct 26, 2015 at 8:56 AM, cheater00 . <cheater00@gmail.com> wrote:
> fwiw, I did this:
>
> sudo btrfs qgroup show /media/X
> ERROR: can't perform the search - No such file or directory
> ERROR: can't list qgroups: No such file or directory
>
> I assume this means no qgroups present, which means no quotas present.
> Please correct me if I'm wrong.
> So yes, the issue must lie elsewhere.
>
> On Mon, Oct 26, 2015 at 2:46 PM, cheater00 . <cheater00@gmail.com> wrote:
>> I don't remember doing that, but just to exclude everything, how do I check?
>>
>> On Mon, Oct 26, 2015 at 2:45 PM, Donald Pearson
>> <donaldwhpearson@gmail.com> wrote:
>>> AFAIK quotas aren't a mount option, but if you never enabled them and
>>> created the qgroups by hand that's your answer and the issue must be
>>> something else.
>>>
>>> On Mon, Oct 26, 2015 at 8:36 AM, cheater00 . <cheater00@gmail.com> wrote:
>>>> There are no quotas. I haven't enabled them. I believe the fstab says
>>>> that - could they be enabled in another way? How do I check for sure?
>>>> The man page doesn't say how to check the status:
>>>> https://btrfs.wiki.kernel.org/index.php/Manpage/btrfs-quota
>>>>
>>>> On Mon, Oct 26, 2015 at 2:32 PM, Donald Pearson
>>>> <donaldwhpearson@gmail.com> wrote:
>>>>> Accidentally didn't reply to the list the 1st time.
>>>>>
>>>>> I see the same issue when I have quotas enabled.  If you have quotas
>>>>> on, see if turning them off helps.
>>>>>
>>>>> On Mon, Oct 26, 2015 at 7:16 AM, cheater00 . <cheater00@gmail.com> wrote:
>>>>>> Hi guys,
>>>>>> I am running into really bad performance. Here's my setup:
>>>>>>
>>>>>> WD Red 6 TB connected over USB2 to my core i7 laptop, running Ubuntu
>>>>>> 32-bit with kernel 4.0.4-040004-generic #201505171336.
>>>>>>
>>>>>> Single btrfs partition covering whole disk.
>>>>>>
>>>>>> Autodefrag is on.
>>>>>>
>>>>>> fstab line:
>>>>>> UUID=... /media/X btrfs rw,nosuid,nodev,autodefrag 0 0
>>>>>>
>>>>>> Sometimes when files are being modified or removed, I see
>>>>>> btrfs-transacti eat 100% cpu; during this time no io operations
>>>>>> succeed, that is, they're all stalled. You can't even ls on that fs.
>>>>>> This happens for several minutes then normal operation resumes. There
>>>>>> doesn't seem to be a rule to what will trigger this, other than
>>>>>> opening a single file and reading usually works quite well. (say,
>>>>>> watching a movie while all other programs are closed). But even moving
>>>>>> files off the disks triggers some sort of bug. Just now I am moving a
>>>>>> few files (just 30gb worth) onto another disk, and the bug triggers.
>>>>>> So btrfs-transacti was eating my cpu for over 5 minutes and according
>>>>>> to mv's output after this was done and cpu usage went back to normal
>>>>>> what I was waiting for was for a tiny png file to be removed. This is
>>>>>> pretty bad.
>>>>>>
>>>>>> I have tried defragmenting directories where files are being accessed
>>>>>> and moved. This hasn't helped.
>>>>>>
>>>>>> This happens whether the FS is near full or not. It currently is near
>>>>>> full but it wasn't before and it still did that. It still has about ~
>>>>>> 100GB free space now.
>>>>>>
>>>>>> The more things are happening the more often this bug gets triggered.
>>>>>> So if I have utorrent running and its temporary downloads directory is
>>>>>> there, its download speed graph will be a few spikes of running at
>>>>>> several MB/sec separated by durations of 0 download speed.
>>>>>>
>>>>>> Nothing seems to show up in dmesg or syslog.
>>>>>>
>>>>>> I have asked in #btrfs but the suggestions ended up not fixing the
>>>>>> issue (autodefrag, defrag dirs).
>>>>>>
>>>>>> Please advise what I should do with this issue.
>>>>>> --
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