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Re: Swap on software RAID1



begin  quotation of Alvin Oga on 2004-07-28 15:41:22 -0700:

> > I've been setting up software RAID1 and am wondering what to do about
> > swap.  According to the Software-RAID-HOWTO
> > (http://www.tldp.org/HOWTO/Software-RAID-HOWTO-2.html), there's
> > apparently an 'ongoing debate' on the virtues of using software RAID1
> > with swap.

<snip>

> on the other hand, if one of the disk died, and you have swap
> on both disk, you can still be using the swap space from the
> remaining disk ... no different than saving data on the remaining disk..
> 
> but if you have un-raided swap, one swap on each disk, you have
> 2x as much swap space ... which can be good or bad ..
> 	- bad, cause swap is slow anyway (raid1 swap will NOT be faster)
> 	- good cause you have 2x more swap than raided swap

I know that raid1 swap will not be faster than two swap partitions of
equal priority; however, I'm more worried about reliability.

If there are two swap partitions on separate drives, and if one drive
fails, I'll lose whatever was swapped out of memory to that drive.
Will that cause a problem; will the operating system expect the
swapped memory to be there, and possibly hang if it's not?  The Debian
rootraid HOWTO (http://alioth.debian.org/projects/rootraiddoc/)
suggests that it might; I'm asking for more definite confirmation.

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