topic Re: FATA Drives as Default Diskgroup on EVA in Disk Enclosures

FATA Drives as Default Diskgroup on EVA

Armin Norouzi — Sat, 30 Jan 2010 06:21:32 GMT

Hi,
I know that HP recommends FC drives for default DG. I have an EVA4400 with only 10 FATA drives and it would be used for archiving purposes only. Will the current configuration work well for me or should I buy 8 additional FC drives for default DG?

Re: FATA Drives as Default Diskgroup on EVA

Víctor Cespón — Sat, 30 Jan 2010 11:34:24 GMT

Default disk group is just the name for the first disk group created when you intialize the EVA. The type and number of disks depends on how many I/Os and MB/s you expect to get from the EVA.

If you're going to do backups (sequential writes) to that EVA, the FATA drives will do well, 80 MB/s writting on a RAID 5.

You need 15K FC drives if you're going to do random reads or writes.

Re: FATA Drives as Default Diskgroup on EVA

Armin Norouzi — Sat, 30 Jan 2010 13:17:56 GMT

Thanks vcespon,
As far as I know, default disk group also stores some metadata (like block tracking info). Now I wonder using FATA drives as default disk group may cause performance impact on the whole EVA. Can you help me?

Re: FATA Drives as Default Diskgroup on EVA

Patrick Terlisten — Sat, 30 Jan 2010 13:34:17 GMT

Hi,

this is stored on the quorum disks. If you add disk groups, one quorum disk of five will be transfered to the new diskgroup. I don't think that this is a big performance impact.

Regards,
Patrick

Re: FATA Drives as Default Diskgroup on EVA

Uwe Zessin — Mon, 01 Feb 2010 19:31:41 GMT

It should not be a big performance impact if you have a static EVA, but I've once worked on a box with CA and an additional FATAl diskgroup. I have not done any real timings, but on that system I got the impression that --configuration-- changes (e.g. DRG/vDisk add or remove) were processed much slower and one of the FATAl disks was flickering like crazy.