Best practice for Array configurations

[Terry Buydos_1]

The server in question (one of 4 identicalones) is a Compaq DL380R01 P866-256 128us .
2-18.8 GB drives, internal drive bays, attached by a Smart Array Controller, Embedded slot
The operating system is Windows 2000 server, service pack 2
Compaq Array Configuration Utility V2.80 A

My question concerns the best method for partitioning the drives.
The disks are to to be partitioned into 3 volumes, an 8GB C: drive for the operating system, a 2GB E: drive for a page pool, and the remaining 8GB as the F: drive for data .
All drives are to be RAID 1(mirrored).
The disks can be either basic or dynamic.

The question:
1. Should the space for the three volumes (c:, e:, and f:) be partitioned out as three logical drives and defined as RAID 1 by using the ACU, then each disk be formatted and volumes made via Disk Management under Windows,
OR
Should a single 18GB RAID 1 logical be created with the ACU, and then that single disk be partitioned into the three volumes via Disk Management under Windows?
We are looking for performance, reliability and flexability issues

[kris rombauts]

Hi Terry,

to reply to the flexibility question,best choice is to create just one logical drive equal to the max array capacity (so logical drive size is equal to the raid1 array size, being 18 Gbyte in this case). Reason why is that it is more flexible to manipulate your disk C:, E: and F: by partitioning at the OS level then at the array (lower) level if you have to modify or extend them later.

From the reliability point of view i see no difference since this is RAID1 and if a disk fails you're still ok no matter if you have one or multiple logical drives created in the raid1 array. In this case with only 2 disks, you can't protect more then what RAID1 offers you really,which is it can survive one disk failure.


From the performance point of view i can't really advise but ideally the NTFS (in case of Windows) block size should match the stripe size with which the array is working with or a multiple of it (i.e. 64 Kbytes). But this is a more complex matter as it depends on the application that you're using and the type of acces.
I am not sure how the array cache memory is divided over the different logical drives as opposed to just one large logical drive and what the impact on performance could be, i don't think it will make much difference in your config anyhow.

regards, Kris