RAID 5 max disk nos

[Guest gjb]

Hi,

 

Is there a recommended or suggested max no of disks that should be placed in

a single RAID-5 array. Recently a SAN engineer suggested that up to 9 is

optimum and that as well as increased risk of multiple disk failure in a

single set, performance is also affected.

We have a no of 15 disk enclosures that historically have been built as

single arrays whereas I think that splitting into 2 x7 with GHS would be

better albeit at the cost of some storage capacity.

Comments appreciated

 

Geejay

[Guest Donald Campbell]

Re: RAID 5 max disk nos

 

In article <ut904HInIHA.2396@TK2MSFTNGP02.phx.gbl>, gjb <gjb@ntl.com>

writes

>Hi,

>

>Is there a recommended or suggested max no of disks that should be placed in

>a single RAID-5 array. Recently a SAN engineer suggested that up to 9 is

>optimum and that as well as increased risk of multiple disk failure in a

>single set, performance is also affected.

>We have a no of 15 disk enclosures that historically have been built as

>single arrays whereas I think that splitting into 2 x7 with GHS would be

>better albeit at the cost of some storage capacity.

>Comments appreciated

>

>Geejay

>

>

 

I have seen 3, 5, 7, 9, 10, 15 disks in RAID 5.

 

They all work well under normal running but the larger number the slower

it is if one fails.

 

On the EMC SANs I work on that have 15 disks to a tray, I tend to slice

into 2 x 7 and a hot spare and use them for the low throughput data

areas. The higher throughput areas I put on 3 x 5.

 

Don C