mirroring setup

[kholikt]

Hi,

I have a server with the following four disk.

A0 0/0/2/0.0
A1 0/0/2/0.2
B0 0/0/1/1.0
B1 0/0/1/1.2

I will install the OS on one disk and swap on another disk.

Both OS and swap will be mirrored. My question is should I use A0 as OS, A1 as the OS mirror. B0 as the swap and B1 as the mirror swap.

What will be better?

[Steven Sim Kok Leong]

Hi,

In the first place, it is unnecessary to mirror your swap device. The system can survive without swap (there is still pseudo-swap which uses the memory), unless you really have insufficient physical memory for your applications.

What if a controller fails? Thus, it is best that you mirror across controllers instead of just across disks. Mirror A0 to B0 or B1 instead of A1.

Hope this helps. Regards.

Steven Sim Kok Leong

[Steven Gillard_2]

I recommend the setup as follows:

A0 -> B0
B1 -> A1

You should mirror across controllers to protect against controller failure. I also think its a good idea to alternate the paths to the primary mirror copy to balance the load a little.

Regards,
Steve

[Trond Haugen]

I agree with Steven regarding where to mirror. Just remember to mirror the primary swap (which I guess will be on the OS disk).

Trond

[Krishna Prasad]

I also agree with Steven.

I would also mirror my swap device. You must mirror the primary swap.

Even if you don't use much swap today who knows what your system will be using in 2,3,4 years. If you application is using swap and the swap device crashes your app will crash.