[CentOS] OT: Quick ext3 command

[Barry Brimer]

> Sorry for the off-topic, but I've just installed CentOS 5 on my home
> box and I want to put the journal on another drive. I created a
> software RAID-1 device, /dev/md1, and formatted an ext3 file
> system on it. Now I want to move the journal to /dev/hda5. I've
> googled for this and the process appears to be:
>
> mkfs.ext3 -b 4096 -O journal_dev /dev/hda5
> mkfs.ext3 -b 4096 -J device=/dev/hda5 /dev/md1
>
> Now, here's the fun part. I've already put data on /dev/md1.
> Will the above commands reformat /dev/md1? If so, is there
> an easy way to move the journal for /dev/md1 to a new
> partition?

These commands will reformat your /dev/md1 device.

I have not tried this, but I would expect the following to work.

1.  Backup your data.
2.  Unmount the filesystem on /dev/md1
3.  Create the external journal with "mkfs.ext3 -b 4096 -O journal_dev 
/dev/hda5"
4.  Use tune2fs to associate the external journal to your 
filesystem with "tune2fs -J device=/dev/hda5 /dev/md1"

HTH,
Barry