Placing FATA disksl good practice

[daanj]

I'm looking for information about good practices about placing FATA disk in EVA arrays. Example: eva4400 and 4 disk encl. 36 FC 15k disks ad 12 FATA disks. Usually the FC disks are in 3 encl and fata disks are in the 4-th. HP engineer toold me some time ago that in no good for performance (but with no details).
Is there a reason to mix fata and fc disk when there are only 3 or 4 disk encl?
Is placing all FATA disk in one encl a mistake? (of course i know about rss but I'm thinking about small deployments, max 4 encl)

[hvhari]

if you are aware of the RSS distribution and is ok with that risk, you can go ahead and populate one enclosure with only fata disks. When you configure disk groups, make sure FC & FATA disks are on different disk groups.

[Johan Guldmyr]

Well, wouldn't it be better for redundancy to spread the disks between the enclosures?

[Torsten.]

>> Well, wouldn't it be better for redundancy to spread the disks between the enclosures?


Of course yes.


I would consider to power off the EVA on next down time, place all FC disks at the left, all FATA disks on the right (just to see it better if you are in front of the chassis) and spread the disk this way across all available disks chassis.

[Sivaramakrishna_1]

i would always prefer stripe the HDDs(what ever either FC or FATA) across the available enclosures. But I do accept that most of the times, if HDDs upgrade, eg: intially array populated with FC later FATA HDD purchased , generally they will put all new HDD in new enclousure.

As explained in previous reply by folks, better if u have a downtime try to populate all FC from 1-9 on all 4 Enclosures and 10-12 with FATA.