I am trying to figure out what the best way to use paging space is with
SW RAID. Should you avoid swapping altogether? Advantages:
a) increased performance since you're not swapping (provided you've got
enough physical memory)
b) decreased risk of filesystem corruption on the RAID array in case the
disk which holds the swap space fails (I am not really sure about this;
is filesystem related information that is cached in memory really
subject to paging? - would seem like a bad idea from this point of view)
c) generally speaking, if your aim is redundancy, and you want the
system to keep going if say, one of the disks in a RAID 1 array fails,
and this disk also holds (part of) the system swap space, then the
processes owning the swapped-out pages would crash, possibly
destabilizing the entire system
Disadvantages:
a) decreased performance if physical memory is exhausted (if you don't
have enough physical memory) b) decreased system stability if physical
memory is exhausted c) I don't really know what happens if physical
memory is exhausted (I've never tried it, or found myself in the
position, or tried setting up a test bed to provoke such a situation)
Also, how would you distribute the swap space across the individual
disks (if you decide you want swap space)? What's the general idea, rule
of thumb, whatever? The HOWTO at
http://www.linuxdoc.org/HOWTO/mini/Software-RAID-8.html
has a section about it under 'Performance, Tools & General Bone-headed
Questions' but this is only about the fact that the kernel will
automatically stripe across equal-priority swap partitions on several
disks (interesting to know), thereby increasing performance.
Any comments are welcome.
Cheers,
Frank
BTW: Is there an archive for this list somewhere, since I am new to it
and thus might ask questions that have been discussed a zillion times
before.
--
frank joerdens
joerdens new media e: [EMAIL PROTECTED]
heinrich-roller str. 16/17 t: +49 30 44055471
10405 berlin f: +49 30 44055475
germany h: http://www.joerdens.de
pgp fingerprint:
_____________________________________________________________
| |
| hockey savagery southward recover |
| playhouse breakaway quiver Atlantic |
| sugar disable befriend positive |
| Geiger company seabird Atlantic |
| prowler amusement commence Montana |
|____________________________________________________________|
