[lxc-users] Limits kind of not working

[Pavol Cupka]

this is strange!

I have changed the quota to 2GB and run dd
dd if=/dev/zero of=/test.file
dd: error writing '/test.file': Disk quota exceeded
0+1 records in
0+0 records out
1982988288 bytes (2.0 GB) copied, 1.7051 s, 1.2 GB/s

if I change it to 20GB dd creates 47GB without problem before I stop it
dd if=/dev/zero of=/test.file
^C0+22 records in
0+22 records out
47244550144 bytes (47 GB) copied, 33.1497 s, 1.4 GB/s

ok it works better with if=/dev/urandom probably because of the
compress=lzo being enabled

thanks for help


On Tue, Sep 12, 2017 at 6:36 PM, Pavol Cupka <pavol.cupka at gmail.com> wrote:
> I want to use btrfs even though it is not "production ready", but I
> like it for the features zfs is missing (balancing, growing/shrinking
> volumes, dedup not eating your ram ...).
>
> I wrote 50GB using dd if=/dev/zero and the quota show is showing this now
> btrfs qgroup show -reF /var/lib/lxd/containers/c1/
> qgroupid         rfer         excl     max_rfer     max_excl
> --------         ----         ----     --------     --------
> 0/528         2.59GiB      1.72GiB         none     20.00GiB
>
> so technicaly speaking it is working because excl is smaller then
> max_excl but in practice 50GB is not smaller than 20GB.
>
> I will try to ask in btrfs mailing list. thank you for your help
>
> On Tue, Sep 12, 2017 at 9:39 AM, Marat Khalili <mkh at rqc.ru> wrote:
>>> so you would recommend ZFS instead?
>>
>>
>> I personally don't use ZFS (it's alien to Linux kernel and I don't want to
>> deal with support problems arising from this situation). Many people claim
>> it's magical and revolutionary, so it's up to you to test and decide.
>>
>> I use LXC on BTRFS with manually-enabled quotas, but I do have problems with
>> it. If you want it simple I'd recommend to either forget quotas or use
>> partitions.
>>
>>> well it looks like it gets set correctly also for btrfs
>>>
>>> btrfs qgroup show -reF /var/lib/lxd/containers/c1/
>>> qgroupid         rfer         excl     max_rfer     max_excl
>>> --------         ----         ----     --------     --------
>>> 0/528         1.02GiB    156.54MiB
>>
>>
>> Not sure why it doesn't work then, try calling `btrfs quota enable` for the
>> filesystem. Are you sure you can really exceed the quota? You have it set
>> for amount of exclusive data, so extents shared with other subvolumes do not
>> count towards it.
>>
>>
>> --
>>
>> With Best Regards,
>> Marat Khalili
>>
>> _______________________________________________
>> lxc-users mailing list
>> lxc-users at lists.linuxcontainers.org
>> http://lists.linuxcontainers.org/listinfo/lxc-users