Disk Enclosures

HP Smart Array - RAID and Logical Arrays

New Member

HP Smart Array - RAID and Logical Arrays

Hopefully a simple answer to what seems to be a fairly simple question...


If, for example, you have a P800 HP Smart Array with 24 disks and a spare and you want to partition a number of database files across drives to maximise I/O performance (the transaction log file is heavy on writes and the other data and index files are heavy on reads), would it be better to:-


a) Use the 24/25 disks to create one SAS Array and three logical drives:-


SAS Array A with spare - 3 Logical drives

     Logical Drive 1 (1200 Gb, RAID 1+0) 
     Logical Drive 2 (1200 Gb, RAID 1+0)
     Logical Drive 3 (1200 Gb, RAID 1+0)


b) Use the 24 disks to create three SAS arrays each with one Logical Drive:-


SAS Array A  & Logical Drive 1  (1200 Gb, RAID 1+0) 
SAS Array B  & Logical Drive 1 (1200 Gb, RAID 1+0) 
SAS Array C  & Logical Drive 1  (1200 Gb, RAID 1+0) 


Not sure how the Spare disk fits into Option B?


Anyway, if the objective is to maximize I/O performance, is it Option A or B?   
The phrase, 'logical drive'... Does this mean that I/O is partitioned at the logical drive level or does the HP Smart array controller spread the I/O across the SAS Array?  If I look at I/O counters (eg. Perfmon on Windows Server), I can see that Logical drives as in Option A seem to be separated completely as one logical drive could have a disk queue and other logical drives on top of the same SAS array will not have a disk queue.  What are the prose and cons of Option A and B?  Understanding these issues will help me to come up with the right configuration in terms of arrrays and logical drives.


Thanks in advance,



Honored Contributor

Re: HP Smart Array - RAID and Logical Arrays

Have you found an asnswer from any source to your question?


I don't know, wich is faster.


But from a security point of view, I would say option B.


Option A:

All data is on all and the same disks. When you create 3 logical drives on an array, its like when you partition a single disk.

You will have LD 1, at the bottom, LD 2 at the mittle and LD 3 at the top.

In case of a disk failure, LD1 wil be rebuild first, then LD 2 and finally LD 3.

If you suffer from a catastrophic disk failure, all is lost.




Accept or Kudo

Mark Matthews
Respected Contributor

Re: HP Smart Array - RAID and Logical Arrays

I would go with option B.
Or even better, an additional array controller, so you'd have one for the OS and the other for your databases.
You should see a nice performance boost then...

I'd definately configure a spare with all those disks, maybe even two.

A spare can be assigned to multiple arrays / logical drives at the same time so it'll cut in for any disk that fails in any logical drive configured on the same controller.


Please click the white Kudos star to the left if this post is helpful :)