[ceph-users] how to improve performance

Nigel Williams nigel.williams at tpac.org.au
Mon Nov 20 15:00:28 PST 2017


On 20 November 2017 at 23:36, Christian Balzer <chibi at gol.com> wrote:
> On Mon, 20 Nov 2017 14:02:30 +0200 Rudi Ahlers wrote:
>> The SATA drives are ST8000NM0055-1RM112
>>
> Note that these (while fast) have an internal flash cache, limiting them to
> something like 0.2 DWPD.
> Probably not an issue with the WAL/DB on the Intels, but something to keep
> in mind.

I had forgotten about the flash-cache hybrid drives. Seagate calls
them SSHD (Solid State Hard Drives) and as Christian highlights they
have several GB of SSD as an on-board cache. I looked at the
specifications for the ST8000NM0055 but I cannot see them listed as
SSHD, rather they seem like the usual Seagate Enterprise hard-drive.

https://www.seagate.com/www-content/product-content/enterprise-hdd-fam/enterprise-capacity-3-5-hdd/constellation-es-4/en-us/docs/ent-capacity-3-5-hdd-8tb-ds1863-2-1510us.pdf

Is there something in the specifications that gives them away as SSHD?


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