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Re: Problems adding swap files

On 15 May 1997, Miquel van Smoorenburg wrote:

> You can stripe swap without using md - the kernel does it for you
> ever since Linux 1.3.2 :)
> Read the "swapon" manpage, option "-p".

The kernel may allocate pages on a round-robin basis, but I'd like to tuck
my swapspace into my md disk for better io performance.  I'm getting
killed on a maxed-out IDE system.

I've got four IDE drives, all Western Digital.  Two 1.2Gs, as master on
primary and secondary (spare, /, swap1, /usr on pri, /local, /var, swap2,
/tmp on sec).  Two 3.1Gs, as slave on primary and secondary (hdb1 and hdd1
comprise the entire disk and are md'd together in RAID0.

I/O is quite good until my mirror runs, which dumps to the md array.
Mirror tends to sit on a lot of memory (24MB for my debian mirror process
alone), and swapping must compete with access to the md array (IDE
drawbacks are becoming quite clear to me....).  Anything else that should
access any system partition in conjunction with the md array also suffers,
but mirror is the biggest killer.

As my system is currently laid out, I'm not suffering from any shortage of
swap _space_ (240MB allocated, max seen in use is 33MB), I'm merely trying
to sneak out the best possible performance without spending a buck.

I think I'm just having trouble using a swapfile on a md array, as opposed
to a pathname problem.  Any ideas would, of course, be gladly accepted.



Peter J. Templin, Jr.                   Client Services Analyst
Computer & Communication Services       tel: (717) 524-1590
Bucknell University			templin@bucknell.edu

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