[kwlug-disc] ZFS pool says it's 100% full according df -h and yet I know there is space as I have remove a lot of files...

Federer Fanatic nafdef at gmail.com
Sun Dec 29 12:07:41 EST 2019


sudo systemctl status sanoid.service
● sanoid.service - Snapshot ZFS Pool
   Loaded: loaded (/lib/systemd/system/sanoid.service; static; vendor
preset: enabled)
   Active: inactive (dead) since Sun 2019-12-29 12:00:03 EST; 5min ago
  Process: 10396 ExecStart=/usr/sbin/sanoid --take-snapshots --verbose
(code=exited, status=0/SUCCESS)
 Main PID: 10396 (code=exited, status=0/SUCCESS)

Dec 29 12:00:01 XXXXX sanoid[10396]: INFO: taking snapshots...
Dec 29 12:00:01 XXXXX sanoid[10396]: taking snapshot
homedirs at autosnap_2019-12-29_12:00:01_daily
Dec 29 12:00:02 XXXXX sanoid[10396]: cannot create snapshots : out of space
Dec 29 12:00:02 XXXXX sanoid[10396]: CRITICAL ERROR: /sbin/zfs snapshot
homedirs at autosnap_2019-12-29_12:00:01_daily fai
Dec 29 12:00:02 XXXXX sanoid[10396]: taking snapshot
homedirs at autosnap_2019-12-29_12:00:01_hourly
Dec 29 12:00:03 XXXXX sanoid[10396]: cannot create snapshots : out of space
Dec 29 12:00:03 XXXXX sanoid[10396]: CRITICAL ERROR: /sbin/zfs snapshot
homedirs at autosnap_2019-12-29_12:00:01_hourly fa
Dec 29 12:00:03 XXXXX sanoid[10396]: INFO: cache expired - updating from
zfs list.
Dec 29 12:00:03 XXXXX systemd[1]: sanoid.service: Succeeded.
Dec 29 12:00:03 XXXXX systemd[1]: Started Snapshot ZFS Pool.


--------------------------------------------------------------
 Roger Federer Fanatic Extraordinaire :-)


On Sun, Dec 29, 2019 at 11:54 AM Benjamin Tompkins <bjtompkins at gmail.com>
wrote:

> So this is actually expected.   Once you get past 80% full on a ZFS pool,
> write performance starts to suffer.  I don't have an article handy
> regarding this at the moment as I am on my phone.
>
> Once some space gets freed you should get performance back.
>
> On Sun., Dec. 29, 2019, 10:28 a.m. Federer Fanatic, <nafdef at gmail.com>
> wrote:
>
>> Seems to be the same problem, no space on device:
>>
>> sudo zdb -M homedirs
>> vdev          0 metaslabs  116 fragmentation 27%
>> 12: 185132 ****************************************
>> 13: 113286 *************************
>> 14:  72563 ****************
>> 15:  67800 ***************
>> 16:  59987 *************
>> 17:  30729 *******
>> 18:  13720 ***
>> 19:   7163 **
>> 20:   4157 *
>> 21:   1977 *
>> 22:    964 *
>> 23:    502 *
>> 24:    254 *
>> 25:     88 *
>> 26:      5 *
>> 27:      3 *
>> 28:      1 *
>> pool homedirs fragmentation 27%
>> 12: 185132 ****************************************
>> 13: 113286 *************************
>> 14:  72563 ****************
>> 15:  67800 ***************
>> 16:  59987 *************
>> 17:  30729 *******
>> 18:  13720 ***
>> 19:   7163 **
>> 20:   4157 *
>> 21:   1977 *
>> 22:    964 *
>> 23:    502 *
>> 24:    254 *
>> 25:     88 *
>> 26:      5 *
>> 27:      3 *
>> 28:      1 *
>>
>>
>>
>> --------------------------------------------------------------
>>  Roger Federer Fanatic Extraordinaire :-)
>>
>>
>> On Sun, Dec 29, 2019 at 9:09 AM Federer Fanatic <nafdef at gmail.com> wrote:
>>
>>> Ok. I think I get what's going on. Available space is being released,
>>> painfully slowly ,
>>>
>>> zfs get all  is show very active processing albeit very slow...
>>>
>>>
>>>
>>> --------------------------------------------------------------
>>>  Roger Federer Fanatic Extraordinaire :-)
>>>
>>>
>>> On Sun, Dec 29, 2019 at 8:35 AM Federer Fanatic <nafdef at gmail.com>
>>> wrote:
>>>
>>>> Looks like some fragmentation is occurring...presumably because disk
>>>> was getting full, I read
>>>> that having dedup setting on can cause some issues, but my
>>>> zfs get all |grep dedup
>>>> homedirs                                       dedup
>>>> off                    default
>>>>
>>>>
>>>>
>>>>
>>>> --------------------------------------------------------------
>>>>  Roger Federer Fanatic Extraordinaire :-)
>>>>
>>>>
>>>> On Sun, Dec 29, 2019 at 8:23 AM Federer Fanatic <nafdef at gmail.com>
>>>> wrote:
>>>>
>>>>> Also zfs get all has a constant stream of output...
>>>>>
>>>>>
>>>>>
>>>>> --------------------------------------------------------------
>>>>>  Roger Federer Fanatic Extraordinaire :-)
>>>>>
>>>>>
>>>>> On Sun, Dec 29, 2019 at 8:19 AM Federer Fanatic <nafdef at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Specifically,  zpool status
>>>>>>
>>>>>>
>>>>>>   pool: homedirs
>>>>>>  state: ONLINE
>>>>>>   scan: scrub repaired 0B in 0 days 03:57:48 with 0 errors on Sun Dec
>>>>>>  8 04:21:49 2019
>>>>>> config:
>>>>>>
>>>>>>
>>>>>>
>>>>>> zpool status yields:
>>>>>>
>>>>>> NAME        STATE     READ WRITE CKSUM
>>>>>> homedirs    ONLINE       0     0     0
>>>>>>  mirror-0  ONLINE       0     0     0
>>>>>>    sda     ONLINE       0     0     0
>>>>>>    sdb     ONLINE       0     0     0
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> # zpool list homedirs
>>>>>>
>>>>>> NAME       SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP
>>>>>>    HEALTH  ALTROOT
>>>>>> homedirs  1.81T  1.76T    57.7G                 -
>>>>>> -    27%      96%  1.00x        ONLINE  -
>>>>>>
>>>>>> which show 1.76 TB. It looks like space is being locked down somehow
>>>>>> and is unavailable and yet
>>>>>>
>>>>>> and yet
>>>>>>
>>>>>> # df -h
>>>>>> homedirs                                      890G  890G     0 100%
>>>>>> /homedirs
>>>>>>
>>>>>> It's as if the volume is shrinking as a I remove files...
>>>>>>
>>>>>> NOTE. It may have something to do with snapshots sanoid settings:
>>>>>> as I am also seeing the mount
>>>>>>
>>>>>> Filesystem
>>>>>>       Size  Used Avail Use%   Mounted on
>>>>>> homedirs at autosnap_2019-12-26_05:00:22_hourly  1.7T  1.7T       0
>>>>>> 100%    /homedirs/.zfs/snapshot/autosnap_2019-12-26_05:00:22_hourly
>>>>>>
>>>>>> ---this goes away if I run systemctl stop sanoid.timer however,
>>>>>> df -h still yes same output as above
>>>>>>
>>>>>>
>>>>>> NOTE. the 1.7TB
>>>>>>
>>>>>> Also removing files from ZFS takes an eternity.
>>>>>>
>>>>>> I am obviously not understanding something.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> --------------------------------------------------------------
>>>>>>  Roger Federer Fanatic Extraordinaire :-)
>>>>>>
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>>
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