[ceph-users] how to improve performance

Christian Balzer chibi at gol.com
Mon Nov 20 15:07:06 PST 2017


On Tue, 21 Nov 2017 10:00:28 +1100 Nigel Williams wrote:

> 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?
> 
The 550TB endurance per year for an 8TB drive and the claim of 30% faster
IOPS would be a dead giveaway, one thinks.

Christian
-- 
Christian Balzer        Network/Systems Engineer                
chibi at gol.com   	Rakuten Communications


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