[ovirt-users] Fwd: Re: Local and Shared storage in same datacenter

Mike maillist at probie.nl
Sun Oct 30 11:14:32 UTC 2016

Hi Barak,

Op 30-10-2016 om 11:19 schreef Barak Korren:
>> While I understand that this makes having local storage impossible, I
>> believe there is a use case to have local storage in a shared storage
>> datacenter.
>> Consider the following:
>> I have a few applications that require 1 milli second latency and at most 2
>> milli second.
>> That is not consistenly achievable with shared storage, to that end I added
>> flash storage to a few hypervisors.
>> About 5% of my servers require this and are not that resource hungry to
>> require a dedicated physical server.
>> That same 5% also has no requirement to be migrated if a host fails.
> I mentioned this in another thread already, please look into the VDSM
> scratchpad hook. It will allow you to attach (files on) the local SSDs
> (as disks) to VMs when those VMs start up. It will perfectly meet your
> use case if you only need to keep the data on the SSD while the VM is
> up.
The data should not be lost if we power down the VM.
If the data is lost during a host failure we have options to restore the 
data, but do not want to do it on a weekly/monthly basis.

The scratchpad is useful for other options we are exploring, thanks!

More information about the Users mailing list