[plug] large swap space and raid array

[Mike Holland]

I'll take a stab at this, hoping someone will correct me if needed.

On Thu, 29 Jan 2004, Denis Brown wrote:

> Basic rule of thumb regarding Linux swap space is to have 2x the amount of
> physical memory, acording to the HOW-TO's.   If multiple disks are

Isn't that more of a "useful limit" than a requirement?
To look at it differently, at least one third of your memory requirements
should be real RAM. (Is that what they mean?)

> available, swap can be split across disks.  I have a system with 2.5G
> physical memory so theoretically I should be running about 5G of swap.

No. Theoretically, your system *may* be able to make use of up to around
that much swap. But general guidlines are less accurate in extreme cases
such as yours.
   Do you expect to have idle processes holding large amounts (GB) of
memory? In that case, swap space will free RAM for use as disk buffering.

> Okay, split up the swap into different partitions across different disks!
> Err... yes, but here I have all my "disk eggs" in one RAID array "basket."

Can't you just create multiple 2GB swap partitions on the same RAID?

> journal in anger).   Given the sheer amount of physical memory, is a
> smaller swap a safe choice (ie.2GB?)

That may still be massive overkill. I'd start with one 2GB swap, and see
how much of it gets used. Possible not much, depending on your software.