4:15 a.m.
On Jan 19, 2018 10:52 AM, "andreil1" <andreil1(a)starlett.lv> wrote:
Hi !
What is optimal setting for oVirt KVM guests for database hosting on Xeon
server (2 x Xeon 4-core each) (in my case this is Firebird based
accounting/stock control system with several clients active)?
1st of course its preallocated disk image.
VirtO-SCSI enabled
- It's not clear that virtio-scsi is faster than virtio-blk in all cases.
Test.
- What's the backend storage?
Migration disabled.
Balloning disabled.
CPU shares disabled
Pass-through host CPU enabled
What about NUMA and pinning?
What should be other CPU settings?
For example, Xeon have 2 threads per core, should I set in oVirt 1 or 2
threads per virtual CPU?
IO Threads on or off?
On.
Any idea of NUMA settings ?
Indeed. + Huge pages, in both host and guest.
Node running 4 VMs total, CPU load is quite low, RAM is enough to
preallocate for each VM + 4GB for node itself.
In short, use high performance VM. See ovirt.org feature page.
Y.
Thanks in advance !
Andrei
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4:31 a.m.
New subject: Q: Optimal settings for DB hosting
On Fri, Jan 19, 2018 at 11:15 AM, Yaniv Kaul <ykaul(a)redhat.com> wrote:
On Jan 19, 2018 10:52 AM, "andreil1" <andreil1(a)starlett.lv> wrote:
Migration disabled.
Why this enforcing? If the VM is so important I see it as a limitation not
to be able to move it in case of need
Pass-through host CPU enabled
I don't know if this is so important.
Tested with Oracle RDBMS and not used in my case.
Any idea of NUMA settings ?
Indeed. + Huge pages, in both host and guest.
Do you think NUMA so essential? It implies non-migratable VM...
In my tests I didn't set NUMA
In short, use high performance VM. See ovirt.org feature page.
Y.
In my opinion the main limitation of "High performance VM" is to be
not-migratable (probably implied because you set NUMA?)
In that case could it be possible to have NUMA as choice, so that at the
same time you can choose if you want a migratable or not-migratable high
performance VM?
Also CPU passthrough, I don't remember if it is included/fixed option in
high perf VM...
Gianluca
12:56 p.m.
New subject: Q: Optimal settings for DB hosting
On Jan 19, 2018 12:31 PM, "Gianluca Cecchi" <gianluca.cecchi(a)gmail.com>
wrote:
On Fri, Jan 19, 2018 at 11:15 AM, Yaniv Kaul <ykaul(a)redhat.com> wrote:
On Jan 19, 2018 10:52 AM, "andreil1" <andreil1(a)starlett.lv> wrote:
Migration disabled.
Why this enforcing? If the VM is so important I see it as a limitation not
to be able to move it in case of need
It's related to CPU pinning and NUMA.
Pass-through host CPU enabled
I don't know if this is so important.
Tested with Oracle RDBMS and not used in my case.
In the specific case of Oracle, I actually suspect you must use CPU pinning
for licensing reasons. I suggest you check.
As for CPU passthrough, might depend on which features you use.
Any idea of NUMA settings ?
Indeed. + Huge pages, in both host and guest.
Do you think NUMA so essential? It implies non-migratable VM...
In my tests I didn't set NUMA
Depends on the workload really. It and CPU pinning are many times critical
for IO bound workloads. Also depends on how much optimization you are
after.
Y.
In short, use high performance VM. See ovirt.org feature page.
Y.
In my opinion the main limitation of "High performance VM" is to be
not-migratable (probably implied because you set NUMA?)
In that case could it be possible to have NUMA as choice, so that at the
same time you can choose if you want a migratable or not-migratable high
performance VM?
Also CPU passthrough, I don't remember if it is included/fixed option in
high perf VM...
Gianluca
2:27 a.m.
New subject: Q: Optimal settings for DB hosting
On Sat, Jan 20, 2018 at 7:56 PM, Yaniv Kaul <ykaul(a)redhat.com> wrote:
On Jan 19, 2018 12:31 PM, "Gianluca Cecchi" <gianluca.cecchi(a)gmail.com>
wrote:
On Fri, Jan 19, 2018 at 11:15 AM, Yaniv Kaul <ykaul(a)redhat.com> wrote:
>
>
> On Jan 19, 2018 10:52 AM, "andreil1" <andreil1(a)starlett.lv> wrote:
>
>
>
> Migration disabled.
>
>
Why this enforcing? If the VM is so important I see it as a limitation not
to be able to move it in case of need
It's related to CPU pinning and NUMA.
Yes. But normally a DB VM is also important form a sla point of view.
So in general one has to find a tradeoff between pure performance and
service level
> Pass-through host CPU enabled
>
>
I don't know if this is so important.
Tested with Oracle RDBMS and not used in my case.
In the specific case of Oracle, I actually suspect you must use CPU
pinning for licensing reasons. I suggest you check.
No. Oracle requires you to license the physical host and all the
hypervisors' farm.
So in my case using SE2 and having for example 3 x 2-cpu hosts composing
the oVirt cluster, you have to license for all 6 sockets.
Done that, you can run how many (non RAC) RDBMS instances inside VMs of
this oVirt cluster.
Unfortunately If you want to run RAC RDBMS your are also enforced to run
single socket hypervisors to respect Oracle licensing for RAC on SE2.
So in my case I didn't use this option.
As for CPU passthrough, might depend on which features you use.
>
> Any idea of NUMA settings ?
>
>
> Indeed. + Huge pages, in both host and guest.
>
Do you think NUMA so essential? It implies non-migratable VM...
In my tests I didn't set NUMA
Depends on the workload really. It and CPU pinning are many times critical
for IO bound workloads. Also depends on how much optimization you are
after.
I saw enabling IO threads was the thing making the greatest difference
inside the VM from an I/O point of view.
I think I cannot disclosure detailed Oracle performance, but in one of my
tests with HP BL460c G9 with E5-2680v4 cpu, I compared Oracle Linux 7.3
with Oracle 12.1 SE2 on both the bare physical server and inside an Oracle
Linux 7.3 VM configued inside it, using HammerDB and the performance was
quite similar in the one VM running on host configuration.
The physical has 2 x 14 core + HT cpus and I configured the VM up to 2:12:2
and so 48 threads in total and 4 IO threads because I have 4 disks
configured at VM level.
I think it doesn't make sense to configure more than 1 IO thread for disk
at VM level, correct?
Under the curtains there is an HP 3PAR with a mix of SSD and SAS disks and
I was able to reach 800-900 MB/s in reads under the VM.
Gianluca
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3 comments
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Yaniv Kaul