[Users] Ploop Random I/O

[Kir Kolyshkin]

On 09/30/2014 08:31 AM, Devon B. wrote:
> You should read more of the resources available at openvz.org: 
> http://openvz.org/Ploop/Getting_started#Resizing_a_ploop_image
>
> There are no specific inode settings for ploop, it creates a private 
> ext4 filesystem for each container, therefore the inode limit is only 
> dependent on the filesystem (ext4).

Right, number of inodes is a function of disk space, is determined at 
filesystem creation,
and can't be changed after that. By default, mkfs.ext4 allocates one 
inode per 16KB of disk space.
You can create a few containers with a different disk space (set during 
creation, i.e.
vzctl create ... --diskspace NNN) and see how it affects disk inodes 
available.

Good news is, when usinig recent tools (vzctl/ploop) you can specify 
disk inodes value
for ploop independent on disk space, by using vzctl create .... 
--diskinodes NNN
(or specifying DISKINODES in sample CT config used when creating a 
container).
Note that the value still can only be set during filesystem creation. 
Try to be realistic
when setting it, don't just set it to a very high value.

Kir.

>
> On 9/30/2014 10:49 AM, Matt wrote:
>> In ploop, can inodes and disk size easily be increased for a container?
>>
>> On Wed, Sep 24, 2014 at 7:34 PM, Kir Kolyshkin <kir at openvz.org> wrote:
>>> On 09/19/2014 11:45 AM, Matt wrote:
>>>> I have a container currently using about 150GB of space.  It is very
>>>> random I/O hungry.  Has many small files.  Will converting it to ploop
>>>> hurt I/O performance?
>>> In case of many small files it might actually improve the performance.
>>>
>>> ploop performance is very close to usual FS, except for then the image
>>> is growing -- this operation somewhat slows it down as it needs to 
>>> allocate
>>> extra blocks and modify the block address table. I guess it's not an 
>>> issue
>>> in your case.
>>>
>>> But don't take my word for it, give it a try yourself!
>>>
>>> Kir.
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