cloudstack-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Marcus <shadow...@gmail.com>
Subject Re: [RFC] adding volume provisioning method option
Date Sat, 01 Feb 2014 06:41:34 GMT
Yes, no_option.img is only 256k in size. it's sparse.

On Fri, Jan 31, 2014 at 11:38 PM, Yoshikazu Nojima <mail@ynojima.net> wrote:
>>I don't think preallocation=metadata is required for sparse qcow2.
>>Just if you want it to NOT be sparse for metadata.
>
> I think it is required. Please see the output below. Only
> "metadata.img" is a sparse file.
>
> ==============
> [root@ut1-qmb-rd5c test]# qemu-img create -f qcow2 -o
> preallocation=off off.img 3G
> Formatting 'off.img', fmt=qcow2 size=3221225472 encryption=off
> cluster_size=65536 preallocation='off'
> [root@ut1-qmb-rd5c test]# qemu-img create -f qcow2 -o
> preallocation=metadata metadata.img 3G
> Formatting 'metadata.img', fmt=qcow2 size=3221225472 encryption=off
> cluster_size=65536 preallocation='metadata'
> [root@ut1-qmb-rd5c test]# qemu-img create -f qcow2 -o
> preallocation=full full.img 3G
> Formatting 'full.img', fmt=qcow2 size=3221225472 encryption=off
> cluster_size=65536 preallocation='full'
> [root@ut1-qmb-rd5c test]# qemu-img create -f qcow2 no_option.img 3G
> Formatting 'no_option.img', fmt=qcow2 size=3221225472 encryption=off
> cluster_size=65536
> [root@ut1-qmb-rd5c test]# ls -alhs
> total 3.1G
> 4.0K drwxr-xr-x  2 root root 4.0K Feb  1 06:29 .
> 4.0K dr-xr-x---. 5 root root 4.0K Feb  1 06:19 ..
> 3.1G -rw-r--r--  1 root root 3.1G Feb  1 06:23 full.img
> 592K -rw-r--r--  1 root root 3.1G Feb  1 06:21 metadata.img
> 136K -rw-r--r--  1 root root 256K Feb  1 06:29 no_option.img
> 136K -rw-r--r--  1 root root 256K Feb  1 06:21 off.img
> ==============
>
>
>>I also remember hearing that either recent qemu-img has a decent
>>preallocation by default now, or that performance has improved such
>>that it doesn't matter. Will need to do some reading to remember, but
>>I think I remember hearing it's not a big deal nowadays.
>
> Ummm. I tested with "qemu-img version 0.12.1," and I confirmed the
> performance of "preallocation=off" is worse than
> "preallocation=metadata",
> but it may be not true with latest qemu. I will test it.
>
> Thank you for your comment!
>
> Regards,
>
>
> 2014-01-31 Marcus <shadowsor@gmail.com>:
>> I don't think preallocation=metadata is required for sparse qcow2.
>> Just if you want it to NOT be sparse for metadata.
>>
>> I also remember hearing that either recent qemu-img has a decent
>> preallocation by default now, or that performance has improved such
>> that it doesn't matter. Will need to do some reading to remember, but
>> I think I remember hearing it's not a big deal nowadays.
>>
>> On Fri, Jan 31, 2014 at 10:04 PM, Yoshikazu Nojima <mail@ynojima.net> wrote:
>>> Hello Nux,
>>>
>>> Thank you for your comment. I will prepare feature specification.
>>>
>>> Regards,
>>>
>>> 2014-01-31 Nux! <nux@li.nux.ro>:
>>>> On 31.01.2014 20:24, Yoshikazu Nojima wrote:
>>>>>
>>>>> Afternoon All,
>>>>>
>>>>> Is there anyone working on adding volume provisioning method option?
>>>>> As you know, thin provisioning of a volume save consumption of a
>>>>> storage, and fat provisioning improves IOPS performance.
>>>>> Especially, Qcow2 can save storage consumption and achive relatively
>>>>> better performance than default by provisioning a volume with an
>>>>> option "preallocation=metadata", which makes an image file a sparse
>>>>> file.
>>>>>
>>>>> http://itscblog.tamu.edu/improve-disk-io-performance-in-kvm/#.232---preallocation
>>>>>
>>>>> Any thoughts about this?
>>>>> If it is ok, I will write a feature specification on confluence and
>>>>> start implementation.
>>>>>
>>>>> Regards,
>>>>> Noji
>>>>>
>>>>>
>>>>> Yoshikazu Nojima <mail@ynojima.net>
>>>>
>>>>
>>>> Hello,
>>>>
>>>> I thought preallocation=metadata is common practice since years. Now I find
>>>> out ACS doesn't actually use it?
>>>> If so, this is really _bad_ and needs to be fixed ASAP...
>>>>
>>>> Thanks Noji
>>>>
>>>> --
>>>> Sent from the Delta quadrant using Borg technology!
>>>>
>>>> Nux!
>>>> www.nux.ro

Mime
View raw message