[PVE-User] Proxmox Ceph Server - SSD OSDs

[Eneko Lacunza]

Hi Alexandre,

Thanks for the info, this at least helps to know that what I'm seeing is 
not strange. :-)

I usually read Anandtech and also Tom's and Storagereview, but haven't 
seen in the reviews/bechmarks any hint about this performance 
differences; they seem to point that datacenter SSDs are only about 
endurance and warranty (and powerloss), and don't have any benchmarks 
that show this kind of differences.

Cheers
Eneko

On 03/12/14 13:16, Alexandre DERUMIER wrote:
>>> - If I look to the spec sheets, 840pro and M550 should give me much
>>> better performance than S3500. What's going on? What should I check on
>>> specs for "real" performance? :-)
> This website have very good benchmark for ssd drives
> http://www.anandtech.com/tag/ssd
>
>
>>> - What real use experience do you have with those or other SSDs for Ceph
>>> OSDs?
> I have tested the s3500 and m550, and m500 is really slow with o_dsync,
> so write are really slow. (400iops for m550 vs 10000iops for s3500 for o_dsync writes)
>
> check this blog to test it
> http://www.sebastien-han.fr/blog/2014/10/10/ceph-how-to-test-if-your-ssd-is-suitable-as-a-journal-device/
>
>
>
> ----- Mail original -----
>
> De: "Eneko Lacunza" <elacunza at binovo.es>
> À: "ProxMox Users" <pve-user at pve.proxmox.com>
> Envoyé: Mercredi 3 Décembre 2014 09:20:22
> Objet: [PVE-User] Proxmox Ceph Server - SSD OSDs
>
> Hi all,
>
> We have recently changed the storage backend of a Proxmox cluster. It
> was using softraid with a SSD drive and a iSCSI drive, and we have
> switched to RBD on a 2 OSD ceph storage.
>
> One of the VMs is quite I/O intensive, as it executes some precalcs
> between 2 DBs every hour.
>
> Our experience has been as follows:
>
> - 1st SSD OSD (inline journal) was a Intel S3500 300GB . This has been
> rocking fast from begining to end, a non-dreamt delight suddenly
> realized. :) Atop reports on peak use ~4% use and 3MB/s write. Much
> better performance than the old storage.
>
> - 2nd SSD OSD (inline journal) was a Samsung 840 Pro 256GB, used in the
> old softraid. This has been a pain from the begining; when it was up
> rebalancing/degradation fix was painfully slow. Finally on peak use it
> wasn't up to the task, so we had to down it to keep the system doing
> usable work. We have checked it with Samsung's Magician, its 24.5TBW
> well bellow 72TBW warranty, but reported performance is bad even after
> firmware update.
>
> - We replaced the 2nd SSD OSD with a Crucial M550 256GB. This hasn't
> been too bad; rebalancing was much quicker than with 840pro, and on peak
> use atop reports ~50% use and 3MB/s write, so we see it up to the task.
>
> Now my thoughts and questions:
> - If I look to the spec sheets, 840pro and M550 should give me much
> better performance than S3500. What's going on? What should I check on
> specs for "real" performance? :-)
> - What real use experience do you have with those or other SSDs for Ceph
> OSDs?
>
> Thanks for reading
> Eneko
>


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