[Users] Re: disk use/empty files question

[Kir Kolyshkin]

On 06/01/2012 01:41 AM, Keith Keller wrote:
> Hello all, thanks for the quick responses!
>
> On 2012-05-31, Kirill Kolyshkin<kolyshkin at gmail.com>  wrote:
>> Assuming you don't have DISK_QUOTA=no in global config (ie /etc/vz/vz.conf),
> That's correct.
>
>> the figures shown come from vzquota, and in order for vzquota to work correctly
>> when you want to copy something to container you have to have it mounted (ie
>> vzctl status 21 should show the word 'mounted' among others) and copy the
>> data to VE_ROOT (ie /vz/root/21) but not to VE_PRIVATE (/vz/private/21).
>>
>> If you have already done it wrong (I assume you did *), you have to recalculate
>> vzquota, the easiest way is to stop container, do vzquota drop 21 and
>> start container
>> again. This should fix your issue.
> You are indeed correct that I originally copied data to /vz/private/21.
> But when I attempted to drop the quota, it still reports 0 blocks used.
> I wonder if Massimiliano's comment is relevant?
>
> On 2012-05-31, Massimiliano
> <massimiliano.sciabica at kiiama.com>  wrote:
>> Hi,
>> I had a similar issue when I first tried to improve performance of VPS
>> with high number of small files.
>> When a VPS reports 0% usage it is usually due to a not ext2 family
>> filesystem. What fs where you using?
> I am using XFS.  The FAQ mentions that disk quotas do not work with XFS,
> so perhaps that's why it isn't displaying quite right (see below).

Right. I am not sure why it behaves this way, but yes indeed, vzquota
doesn't work with XFS.

>
>> I believe this is because of file system crash and the fsck (or journal replay)
>> which truncated your files. In other words, this is not directly
>> related to what you have described above.
> Perhaps--on boot, I didn't notice any unusual messages from fsck, though
> I admit I wasn't paying an enormous amount of attention, and the logs
> don't have anything interesting to report either.  Does OpenVZ do a lot
> of caching of disk writes from within a container?  (It's obviously too
> late now to see what xfs_repair thinks of the filesystem, but FWIW it
> didn't find anything unusual.)
>
>> Speaking of kernel crashes, it's nice to have some console logger installed,
>> such as netconsole so whenever you have an oops you can report the bug.
>> See http://wiki.openvz.org/Remote_console_setup
> Yes, I just set this up after the first crash--silly oversight not to
> have done it right away.  :)
>
>>> # Disk quota parameters (in form of softlimit:hardlimit)
>>> DISKSPACE="1000G:2000G"
>> It looks like you have set disk quota values to more than your really
>> have. Since this doesn't make sense
>> my question is -- did you meant to disable disk space limit entirely?
>> If yes, you can just have
>> DISK_QUOTA=no in this config.
> Well, I am not entirely sure what I want, to be honest.  If it's true
> that having VE_ROOT and VE_PRIVATE on an XFS filesystem means disk
> quotas don't work right, then perhaps I should either use ext3 (or
> ext4?) on that filesystem, or disable disk quotas for all containers.
>
> As an experiment on the latter, I set DISK_QUOTA=no in vz.conf, and now
> I get:
>
> # vzctl exec 21 df -h
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/simfs            1.0T  332G  693G  33% /
> none                   16G  4.0K   16G   1% /dev
>
> But it would be convenient to have disk quotas.  Is there a preference
> for ext3 or ext4 for the host filesystem?

Ext4 of course.

And then I recommend to try using ploop layout not simfs one.
http://wiki.openvz.org/Ploop/Getting_started

>
> --keith
>
>