[Tfug] HDD size and RAID queries

[Nick Lopez]

On May 8, 2013, at 4:49 AM, John Gruenenfelder <jetpackjohn at gmail.com> wrote:
> But, the time has come to upgrade.  Mostly because of MythTV, I find I am
> constantly on the verge of running out of space.  I've already had to resort
> to some symlink juggling to put things in different places where more space is
> fre.
  MythTV added the ability to have multiple recording directories and put new recordings where there is space a version or two ago.

> The argument to ditch RAID-5 in favor of RAID-6 is entirely based on
> probabilities and the likelyhood of encountering an unrecoverable error while
> rebuilding an array.  Am I actually in this realm with these drive sizes?  Is
> my Big Array even remotely close to the Big Array these authors are concerned
> with?  If it's not, then I can stay with RAID-5 and gain an extra 25% usable
> disk space.  Confusing…
  For 4 drives RAID5 is fine

> The other related question deals with using these new giant drives to begin
> with.  I came across a few vague sentences that *seemed* to indicate that the
> current BIOS methods for accessing large drives (LBA) won't do the trick for
> these 1 TB+ drives and that UEFI is required.  Is this really true?  The
> motherboard they will be used with is not new, nor is it very old either.
> I've used 1 TB+ drives on a much older machine at work, but they were accessed
> via USB2 and FireWire and not via a SATA or eSATA port.  Since I saw this
> mentioned in only one place I tend to think that this isn't true, but I
> thought I should check first.
  That mess only matters when booting, once Linux is up it can see everything, and since you already had boot partitions set up at the beginning of the drives you're safe.

  As others have mentioned, fancier file systems can be fun too. ZFS on Solaris or FreeBSD is supposed to be really solid but on Linux it was in the "it might not freak out and destroy all your data stage". BTRFS is in roughly the same level of development; maybe more confident in integrity but the tools are rougher. I recently used BTRFS's mirroring magic to move my laptop from a HDD to an SSD hot, but I had to compile my own kernel to remove the HDD because the version in Debian doesn't have the code to remove a mirror implemented. It did work completely online though.

   - nick