Talk:RAID

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Revision as of 18:00, 27 February 2012 by AskApache (Talk | contribs) (Alternate setups and filesystems)

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Alternate setups and filesystems

Just wanted to mention these directions worked great for me. It would be nice to have more examples for alternate setups and good ideas for filesystems, etc..

AskApache 15:07, 22 February 2012 (EST)

Hey AskApache, it's really rewarding to hear that this article was helpful. I spent a fair amount of time modifying and updating the old Installing with Software RAID or LVM article. Unfortunately, I was never able to spend enough time updating this article. Thankfully, 6arms1leg has made some excellent contributions, along with yourself.
Anyway, could you explain what alternate setups might apply? The filesystem question is an interesting one. I didn't realize there are alternatives to Linux raid auto. And that the Non-FS data allows you to format the array with any filesystem. After some quick searching, the Optimum RAID article on Linux Pro Magazine looks like a good place to start.
~ Filam 09:51, 23 February 2012 (EST)
Sure Filam, basically I would like more advanced and basic information about everthing! But specifically partioning and filesystems.
Partitioning
  • If you have 5 disks of different sizes, and the smallest disk is 500GB and the largest disk is 1.5TB, you can create a raid array on all 5 by creating a 500GB partition on each disk and use those partitions to create the array.
  • Some people using raid like to create a swap partition on each disk and then make a raid 0 array out of those for a fast swap (which is actually kind of redundant as swap already does raid 0 like striping when given multiple swaps with the same priority).
  • Back to the 5 disks, you could create a 100GB partition on each disk and create a raid 0 array out of that for a super fast /usr, /var, /lib directories which can be replaced in case of data loss. And then create 400GB partition on all 5 disks and create a raid 5 array on those partitions for a fast yet data-redundant /home/ directory.
Filesystems
  • You can create any filesystem on a raid array, but some are noticeably better than others. The same things apply here that are mentioned in the Maximizing Performance article.
  • Basically, XFS might be the best to use for a backup raid array containing large backup files, while reiserfs or ext4 might be the best for /home/.
  • When making an XFS filesystem on a raid array, XFS automagically recognizes it is a raid device and optimizes the XFS filesystem settings for you, however ext and reiserfs may need tweaked settings for optimization.
  • Filesystem settings correlate to the chuck-size and other mdadm options in the initial array creation as well, and should be factored in before creating the array.
Wishlist
  • More instructions on backing up partition tables and maybe even how to restore (good excercise to leave to reader)
  • Different ways to mount the devices in /etc/fstab
  • How to test speed
  • More instructions on customizing the mdadm.conf file
I'm working on this too but probably won't be editing anything again for awhile.. Thanks for this article!
--AskApache 13:00, 27 February 2012 (EST)