Thanks for your reply.
> > Let's consider both cases:
> > Journals on SSDs - for writes, the write operation returns right after
> > data lands on the Journal's SSDs, but before it's written to the backing
> > HDD. So, for writes, SSD journal approach should be comparable to having
> > a SSD cach
Hey,
Which one's "better": to use SSDs for storing journals, vs to use them as a
writeback cache tier? All other things being equal.
The usecase is a 15 osd-node cluster, with 6 HDDs and 1 SSDs per node.
Used for block storage for a typical 20-hypervisor OpenStack cloud (with
bunch of VMs running
> yes SSD-Journal helps a lot (if you use the right SSDs)
>
What SSDs to avoid for journaling from your experience? Why?
>
> > We're seeing very disappointing Ceph performance. We have 10GigE
> > interconnect (as a shared public/internal network).
> Which kind of CPU do you use for the OSD-hosts?
period.
>
>
>
> SSD journals will help your write latency, probably going down from around
> 15-30ms to under 5ms
>
>
>
> *From:* ceph-users [mailto:ceph-users-boun...@lists.ceph.com] *On Behalf
> Of *Piotr Wachowicz
> *Sent:* 01 May 2015 09:31
> *To:* ceph-u
Is there any way to confirm (beforehand) that using SSDs for journals will
help?
We're seeing very disappointing Ceph performance. We have 10GigE
interconnect (as a shared public/internal network).
We're wondering whether it makes sense to buy SSDs and put journals on
them. But we're looking for
Hey,
We keep hearing that running Hypervisors (KVM) on the OSD nodes is a bad
idea. But why exactly is that the case?
In our usecase, under normal operations our VMs use relatively low amounts
of CPU resources. So are the OSD services, so why not combine them? (We use
ceph for openstack volume/im
