[mythtv-users] An LVM'd drive died! What do I do...

Brandon Beattie brandon+myth at linuxis.us
Thu Oct 27 14:57:09 EDT 2005


On Thu, Oct 27, 2005 at 05:04:14PM +0100, David wrote:
> (and shrinking - if you happen to be the one geek in the world who uses
> less disk space over time) and reallocation of space.

Let me explain my current setup and give you one of many reasons 
someone may want to shrink a FS, and why I'm not the only one who 
will ever use shrink.

I have /, /media, and /recordings.  / is the only non LVM filesystem.
/media started off as 30GB, /recordings was 1.3TB.  /media exists on a
single drive, hda (Same as /).  Myth records shows all day to the 1.3TB
filesystem.  I have /media as an LVM but only spanning one disk because
if any other the other 5 drives making up /recordings (My large FS) goes
out, I don't lose anything but tv shows.  As time goes on and I store a
new DVD of mine to /media I begin to run out of space.  At this point I
*shrink* /recordings 10GB and give that space to /media.  Make sense?
If I do lose hda I have to re-scan my dvd's, but that's a 1/6 chance,
which is better than 6/6 chance.  This requires shrinking, unless I want
to setup the entire hda for /media and let the free space sit there
unutilized until I fill it with dvd's.  Why do that then /recordings can
use it over and over?

I accept change, it happens.  If you don't believe things change than
don't ever worry about shrinking, or even using LVM.  I know how to
balance priorities and data, and this requires functionality such as
shrink.  I also know how to not waste space.  People are so used to
never changing a partition size that they can't accept new features like
shrink and grow.  But if you want to manage space between partitions,
for whatever reason, you obviously have to shrink one if you're not 
adding more total space.

Here's another one.  A user gets 4 drives, doesn't have a PCI ide card.
He wants to upgrade his 20GB drive to a 200GB drive.  Without shrinking
the FS enough to clear the space off the 20GB drive he never could
install the 200GB.  But then if he used XFS or JFS (Which I like more
than ReiserFS) He couldn't shrink, since JFS and XFS don't support
shrinking, but noone tells this person that until he's cleared the space,
bought the drive, and now has to delete his entire lvm setup to add the
new disk, and lose all his data.  When this whole Raid threat started,
noone told the user "you need 4 identical drives if you want to use the
disks to their max".  If the user had a 50GB and 7 500GB drives he'd
have to have 2 raid 5 partitions, then use LVM to put together.  Then
he gets confused why grub or lilo won't boot Raid 5. :-/  I've
seen this happen 5 times on mythtv-users.

--Brandon


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