[Users] ploop and trim/ discard support

[Kir Kolyshkin]

On 09/13/2012 01:38 AM, Corin Langosch wrote:
>
> On 12.09.2012 at 21:34 +0200, Kir Kolyshkin <kir at openvz.org> wrote:
>>
>> On Sep 12, 2012 11:20 PM, "Corin Langosch" <info at corinlangosch.com 
>> <mailto:info at corinlangosch.com>> wrote:
>> >
>> > Hi,
>> >
>> > it seems that when creating & deleting files inside a ploop backed 
>> container the backing image file doesn't shrink. So the image file is 
>> still consuming around 400 GB, while in the container df shows only 
>> 100 GB in use.
>> >
>> > ll on host: -rw------- 1 root root 384G Sep 12 21:06 root.hdd
>> > df on container: /dev/ploop1           493G  103G  390G  21% /
>>
>> We have online shrink. It's "ploop balloon discard" or just "vzctl 
>> compact". You'd better have ploop and vzctl from git (both are really 
>> close to be released).
>>
>
> The system's still working heavily but the image is already reduced by 
> around 60 GB so it seems to work well. :)
>
> Would you suggest putting some script into crontab to compact all 
> ploop images ex. once a week? Or probably do something like ctid%7 and 
> compact a few of them every night?

You can use ploop balloon discard --stat to find out how much space 
could be compacted, and decide if you need it.

Any contribution in that area is welcome :)

>
> BTW: the man of vzctl contains the "compact" command. But the usage 
> output of vzctl doesn't. Shall I file a bug report for it?

NP, I have just fixed it
http://git.openvz.org/?p=vzctl;a=commitdiff;h=60e4b4

But the big problem here is vzctl --help output is too heavy.
I would like to have something that is done for ploop -- you get basic 
help and if you specify a command you get a command-specific help.

Good patches for that are welcome :)
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