Re: Best way to set up swap for high availability?

[Stephen C. Tweedie]

Hi,

On Fri, 26 Nov 1999 18:04:27 +0100, Martin Bene <[EMAIL PROTECTED]> said:

> At 11:35 25.11.99 +0100, Thomas Waldmann wrote:
>> What's more interesting for me: how about swap on RAID-5 ?

> Personaly, I've only used raid1, but I can give you a quote from Ingo - and
> he should know:

> At 14:49 14.04.99 +0200, Ingo Molnar wrote:
>>> Hmm? Since when does swapping work on raid-1? How about raid-5?
>> 
>> i've tested it on RAID5, swapping madly to a RAID5 array while parity is
>> being reconstructed works just fine.

Sorry, but since then we did find a fault.  Raid resync goes through the
buffer cache.  Swap bypasses the buffer cache.  There is no coherency
between the two activities.  It is possible for raid1 and raid5
background resync to corrupt swap writes to the partition during
reconstruction.

We need to fix this anyway, since the same problem bites journaling. 

--Stephen