Hi Gerald, I think you have to consider that if you use RAID5 logical drives, you have to calculate and write a parity every time you write any data on the disk: so if you have a write intensive application, RAID5 is not so efficient as other RAID protections (1,10, etc); if you have instead read-intensive applications RAID 5 is a good choice because it gives you the possibility to use more physical drives concurrently. Furthermore RAID 5 is the most efficient protection regarding the optimal usage of the available phisical capacity, and it is more and more efficient as the number of physical drives in the array increase; but at the same time as the number of physical drives increase, the performance goes down (because you have to calculate the parity on a larger number of blocks): probably the best compromise is a number of 7/8 disk drives/array. I hope this helps.
Cordiali saluti / Best regards
Gianluca Perilli
Gianluca Perilli
Tivoli Customer Support
Via Sciangai n� 53 - 00144 Roma (Italy)
Tel. 06/5966 - 4581
Cell. 335/7840985
Gerald Wichmann
<gwichman@ZANTAZ. To: [EMAIL PROTECTED]
COM> cc:
Sent by: "ADSM: Subject: allocating disk volumes on
RAID5 array
Dist Stor
Manager"
<[EMAIL PROTECTED]
.EDU>
28-05-02 21.14
Please respond to
"ADSM: Dist Stor
Manager"
Since a RAID-5 array shows up as one big filesystem, what's the best
strategy for determining how many and of what size disk pool volumes to
create for your primary disk storage pool? For the most part I don't think
it really matters unlike allocating volumes on individual disks but perhaps
I'm not considering something.
Thanks..
