[Users] Virtual Disk creation - really slow (config issue?) e.g 20GB disk created in 23 mins - NFS server/Gigabit switch - can anyone suggest why speed is so slow ? (at this rate it would take 1hr 40 mins to create a 100GB disk...)

[Morgan Cox]

Many thanks Gary



On 25 March 2012 02:25, Gary Scarborough <virtuallymad at gmail.com> wrote:

> It can.  I have seldom had need to worry about it.  Most data centers have
> battery backups to keep power outages from crashing systems. I am also not
> sure if its any more or less of a risk than iscsi, except you may not be
> able to tell right away.  async works by basically lying to the client
> about the read/write.  Keep in mind that the read/write may be into a
> virtual machine in this case.  Even if all packets are accounted for, not
> completing the full stream of writing could lead to a corrupt VM filesystem
> anyway.  In my mind, its worth the risk for the speed.  This is also why we
> do backups.
>
>
>
> On Fri, Mar 23, 2012 at 7:48 AM, Morgan Cox <morgancoxuk at gmail.com> wrote:
>
>> Thank you Gary.
>>
>> After re-mounting the NFS share with async it dramatically increased the
>> speed !
>>
>> I can now create a 10GB virtual disk in 2 mins (rather than 10 mins)
>>
>> Is using the async option more likely to cause data corruption though ?
>>
>> Many thanks
>>
>> Regards
>>
>> On 22 March 2012 21:54, Gary Scarborough <virtuallymad at gmail.com> wrote:
>>
>>>
>>>
>>> On Thu, Mar 22, 2012 at 12:59 PM, Morgan Cox <morgancoxuk at gmail.com>wrote:
>>>
>>>> Hi.
>>>>
>>>> After my many issues with spice I have finally sorted them out.
>>>>
>>>> Now I am having an issue with the speed of virtual disk creation - when
>>>> I go to create a virtual disk it takes a long time (far to long to
>>>> be usable)
>>>>
>>>> My setup is as following
>>>>
>>>> 3 servers:-
>>>>
>>>> 1 Frontend (ovirt engine) - Fedora 16    - external + local IP
>>>> (91.215.xxx.xx + 10.0.0.10)
>>>> 1 Ovirt node (using the node .iso)   - external + local IP (ovirtmgmt
>>>> (eth0) - 91.215.xxx.xxx  and LAN (eth1) - 10.0.0.101)
>>>> 1 NFS storage - external + local IP - I attached the storage using the
>>>> Local IP (10.0.0.190)
>>>>
>>>> All servers are connected via a Gigabit switch (so speed should be
>>>> better)
>>>>
>>>> I can scp between servers far faster - I'm almost sure its due to the
>>>> node ovirtmgmt address being an external (internet ip) and not LAN ip.
>>>> - therefore the traffic is not just going over the gigabit switch but via
>>>> the core router in the DC...
>>>>
>>>> Can anyone suggest how I can 'debug' where the slowness is coming from
>>>>
>>>> On my NFS server I have it setup like (in /etc/exports)
>>>>
>>>> /storage1       *(rw,sync,no_subtree_check)
>>>>
>>>> I had previous tried setting up the node on a LAN IP previously and it
>>>> caused spice to not work - as the node had no internet access / DNS - I
>>>> also tried making the frontend server a gateway (and using -  iptables -t
>>>> nat -A POSTROUTING -j MASQUERADE ) - this also cause spice to not work (as
>>>> it always tried to connect to the 10.0.0.x address from my desktop - and
>>>> fail..)
>>>>
>>>> Any hints/help will be welcomed
>>>>
>>>> Cheers
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Users mailing list
>>>> Users at ovirt.org
>>>> http://lists.ovirt.org/mailman/listinfo/users
>>>>
>>>>
>>> You could try async instead of sync.  You could also try thin
>>> provisioning.
>>>
>>> --
>>> Gary Scarborough
>>> IST Lab Manager
>>> Rochester Institute of Technology
>>> Rochester NY
>>>
>>
>>
>
>
> --
> Gary Scarborough
> IST Lab Manager
> Rochester Institute of Technology
> Rochester NY
>
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