--- On Thu, 19/5/11, Stan Hoeppner <stan@hardwarefreak.com> wrote:

From: Stan Hoeppner <redacted>
Subject: Re: Best way to create RAID-6 for swap partition - existing one failed
To: "Gavin Flower" <redacted>
Cc: linux-raid@vger.kernel.org, neilb@suse.de, mb@gem.win.co.nz
Date: Thursday, 19 May, 2011, 6:59
On 5/16/2011 4:41 PM, Gavin Flower
wrote:

quoted

Motivation, existing RAID-6 swap partition

failed.  I am thinking I should recreate it in a new
format, as currently it is 'Version : 0.90', rather than
simply rebuild it.
<snip>

Forget using a partition.  Simply use a swap
file.  This example creates
a 1GB swap file in the / filesystem.  You can locate
it on any
filesystem you wish.

# swappoff -a
# dd if=/dev/zero of=/swapfile1 bs=1024 count=1048576
# mkswap /swapfile1
# swapon /swapfile1
# vi /etc/fstab
Add:
/swapfile1 swap swap defaults 0 0

and remove your old entry for the failed swap partition.

There is little performance difference between swap files
and swap
partitions with modern kernels.  The kernel will map
the disk location
of the swap file and perform direct disk access, bypassing
the
filesystem and buffer cache.

-- 
Stan

Thanks.

Interesting!

(Reminds me of when I first got into Linux.  Then you could have any size swap file up to 128 MB, and have up to 8 swap files, for a maximum of 1 GB. I then had about 64 MB of RAM - now I have 8 GB of RAM. Also, swap partitions were recommended.  When the 2.4 kernel first came out, it was said to be faster if you had at least 16 MB.)

I read up and could not see any benefit in changing, so I ended up 'simply' reassembling the partition.

The 2 things I had thought of altering, were the version of the super block and the chunk size. With the amount of RAM I have, performance is not normally an issue, I was thinking of reliability.  The badblocks run did not reveal any problems, nor did checking the smart diagnostics in detail reveal anything significant.  I think it was some kind of kernel error, transient anyhow.

SUGGESTION:
Could we please have some explanation of the benefits and tradeoffs between the different values of things like chunk size and super block version.
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