[one-users] datablock - poor performance

[Shankhadeep Shome]

qcow3 is supposed to address the qcow vs raw performance. The thing is
qcow2 is so powerful as an image format it hardly makes sense to use
anything else for os drives, at least in my opinion. If you need good
performance, use a combination of qcow2  for transient storage and raw+lvm
for persistent storage.


On Fri, Jun 21, 2013 at 6:26 PM, Ruben S. Montero
<rsmontero at opennebula.org>wrote:

> Hi
>
> Try adding CACHE='none' in each DISK in the **VM template** to increase
> the performance. Usually qcow2 perform worse than raw format, because of
> the additional formatting needed.
>
> If you want to test qcow2 you need to set DRIVER="qcow2" to the DISK
> attribute or image template. Additionally if the TM_MAD attribute of the
> datastore is set to qcow2 (e.g. onedatastore update), some operations take
> advantage of the qcow format, mainly snapshot to clone a disk.
>
> Cheers
>
> Ruben
>
>
>
> On Fri, Jun 21, 2013 at 11:41 PM, Andrei Vakhnin <
> andrey.a.vakhnin at nasa.gov> wrote:
>
>> Hello,
>>
>> I am wondering if qcow2 datablock gives a better performance over raw
>> format. Do I have to use separate datastore to be able to use qcow2 images?
>>  I am getting performance hit (only 12MB/s) when using 50GB non-persistent
>> raw datablock formatted as ext3. Thanks
>>
>> 200000+0 records in
>> 200000+0 records out
>> 1638400000 bytes (1.6 GB) copied, 157.853 s, 10.4 MB/s
>>
>> real    2m40.021s
>> user    0m0.042s
>> sys     0m3.839s
>>
>> oneadmin at xxx:~> oneimage show 38
>> IMAGE 38 INFORMATION
>> ID             : 38
>> NAME           : data_loc
>> USER           : oneadmin
>> GROUP          : oneadmin
>> DATASTORE      : default
>> TYPE           : DATABLOCK
>> REGISTER TIME  : 12/05 15:34:46
>> PERSISTENT     : No
>> SOURCE         :
>> /var/lib/one/datastores/1/bee8c51f03a40657a114ee3cf505d2a1
>> FSTYPE         : ext3
>> SIZE           : 48.8G
>> STATE          : used
>> RUNNING_VMS    : 2
>>
>> PERMISSIONS
>> OWNER          : um-
>> GROUP          : ---
>> OTHER          : ---
>>
>> IMAGE TEMPLATE
>> DESCRIPTION="/data_loc"
>> DEV_PREFIX="sd"
>> DRIVER="raw"
>> TARGET="sdc"
>>
>> Here is a template:
>>
>> DISK=[
>>   BUS="virtio",
>>   DRIVER="raw",
>>   IMAGE_ID="52",
>>   READONLY="no",
>>   TARGET="sdb" ]yes
>>
>>
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>>
>>
>
>
> --
> --
> Join us at OpenNebulaConf2013 in Berlin, 24-26 September, 2013
> --
> Ruben S. Montero, PhD
> Project co-Lead and Chief Architect
> OpenNebula - The Open Source Solution for Data Center Virtualization
> www.OpenNebula.org | rsmontero at opennebula.org | @OpenNebula
>
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