Hi Jay, Ha, I'm sure there's some wisdom hidden behind the trolling here?
Believe me, I have tried to push these sorts of use-cases toward volume or share storage, but in the research/science domain there is often more accessible funding available to throw at infrastructure stop-gaps than software engineering (parallelism is hard). PS: when I say ephemeral I don't necessarily mean they aren't doing backups and otherwise caring that they have 100+TB of data on a stand alone host. PS: I imagine you can set QoS limits on /dev/null these days via CPU cgroups... Cheers, On Thu., 14 Jun. 2018, 00:03 Jay Pipes, <jaypi...@gmail.com> wrote: > On 06/13/2018 09:58 AM, Blair Bethwaite wrote: > > Hi all, > > > > Wondering if anyone can share experience with architecting Nova KVM > > boxes for large capacity high-performance storage? We have some > > particular use-cases that want both high-IOPs and large capacity local > > storage. > > > > In the past we have used bcache with an SSD based RAID0 write-through > > caching for a hardware (PERC) backed RAID volume. This seemed to work > > ok, but we never really gave it a hard time. I guess if we followed a > > similar pattern today we would use lvmcache (or are people still using > > bcache with confidence?) with a few TB of NVMe and a NL-SAS array with > > write cache. > > > > Is the collective wisdom to use LVM based instances for these use-cases? > > Putting a host filesystem with qcow2 based disk images on it can't help > > performance-wise... Though we have not used LVM based instance storage > > before, are there any significant gotchas? And furthermore, is it > > possible to use set IO QoS limits on these? > > I've found /dev/null to be the fastest ephemeral storage system, bar none. > > Not sure if you can set QoS limits on it though. > > Best, > -jay > > _______________________________________________ > OpenStack-operators mailing list > OpenStack-operators@lists.openstack.org > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators >
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