Re: [Moosefs-users] SSDs (was: fox and bird)

[Ricardo J. B. <ric...@da...>]

El Viernes 30/03/2012, Dr. Michael J. Chudobiak escribió:
> On 03/30/2012 06:49 AM, Michał Borychowski wrote:
> > Hi Michael!
> >
> > Do you use only SSD drives in the chunkservers? Maybe you would like to
> > share some speed tests with the users on the group?
> >
> > And do you have SSD disk in the master server? How big is your metadata?
> > Have you noticed any improvements?
>
> Michał,
>
> I have a small moosefs system holding ~400 GB of data, including user's
> home folders.
>
> The master server always had SSD disks. metadata.mfs is only ~50 MB.
>
> Performance was quite disappointing until I removed the two 1TB hard
> drives in the chunk servers and replace them with four 600 GB SSDs. The
> improvement in performance was HUGE. For a small system, they are
> definitely worth the cost.
>
> Here is a quick test I did in a live system, comparing a 600 GB SSD in
> one chunkserver with a 1TB hard drive in the other:
>
> http://i.imgur.com/J0wxz.png

Wow, those are really awful numbers for the 1 TB drives.

Do those drives happen to have 4 KB physical block size?
That combined with unaligned partitions could explain such bad performance.

Check for example:
http://www.ibm.com/developerworks/linux/library/l-4kb-sector-disks/index.html?ca=dgr-lnxw074KB-Disksdth-LX

Regards,
-- 
Ricardo J. Barberis
Senior SysAdmin / ITI
Dattatec.com :: Soluciones de Web Hosting
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