[mythtv-users] advise/suggestions on how to set up my drives?

[Joseph Fry]

>
> sorry, I should have been more specific. I already have the OS/SQL on
> a seperate 7200rpm 40GB MB cache drive. What I'm trying to figure out
> is the best way to set up the three 1.5TB drives to be used as a
> media/recordings drive. all the recordings and DVDrips/ripped
> music/etc will go on this, so I'm interested in what will give me the
> best combination in speed for writing/reading for recordings (two
> firewire tuners one clearQAM tuner) and of course size. Of course it
> would be nice to have some level of redundancy for the media stuff
> (dvd/music rips). So one option is obviously RAID 5 across the drives,
> which if they decide they want more space they can always add more
> drives to the array. This I know is good for redundancy and ok for
> speed. But are there other options I should look at?
>
Adding more drives to a RAID 5 array is not trivial... usually requires a
backup, then you break the array, then build a new array, finally restore
your data.  With high end controllers, careful choice of file system, and
LVM you might be able to resize on the fly... but it's still risky and a
backup would be HIGHLY recommended.

A lot of people don't realize that with software raid, you don't raid the
disks you raid the partitions.  On my server I have 3 drives with a small
partition at the start of each disk (disk 1 is boot, 2 and 3 are swap).  The
next partition on each disk is raid 1 across all 3 drives for my database.
Sure it takes longer to write to all 3, but reads are very fast.  Finally, I
mirror the remainder of two of the drives for my movie/music collection and
use the remainder of the third for television.

Drive 1:
   P1 - boot
   P2 - MD0 (mirroring)
   P3 - MD1 (mirroring)

Drive 2:
  P1 - swap
  P2 - MD0 (mirroring)
  P3 - MD1 (mirroring)

Drive 3:
  P1 - swap
  P2 - MD0 (mirroring)
  P3 - Standard data partition.

This setup yields almost as much space as a software raid 5 setup (other
than the small DB array it's the same amount of usable storage)... but is
faster, has less CPU overhead, and has equal or better fault tolerance for
the data I am concerned about.  (database  can handle a 3 drive failure,
movies/music a single drive failure, tv... who cares).
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