[mythtv-users] OT: Second SATA on Promise 376 controller? (Happy
Linux.Luser at myrealbox.com
Sun Dec 26 00:39:24 UTC 2004
On Dec 25, 2004, at 8:26 pm, GERALD SCHEPENS wrote:
> ... I just want to add another couple hundred gigs without having to
> totally reformat, etc.
> Also, can a person take a non-LVM'd drive such as mine is currently
> and begin using LVM with it and another drive, again without wiping
> the existing disk?
This is fairly straight-forward, at least once you've done it the first
time. The important thing to remember is that a logical volume looks to
the filesystem as just another partition - it can be resized easily &
it can span more than one physical drive, but it can be referred to as
/dev/volumes/something, in the same way that conventional partitions
are referred to as /dev/hda1 &c.
I haven't started building a mythtv box, yet, but presumably you have
all your films in a directory such as /var/mythtv/movies or
/home/mythtv. If you don't already have this as a mount point for a
partition then things are a bit more involved, so let's start by
assuming everything you want on LVM is already in a separate partition
which you can format after you've moved it:
- First, shutdown the PC, add the new hard-drive & restart.
- Next, initialise the new drive with `pvcreate`, create & activate
your logical volume group, add the new drive to it and create & format
a logical volume of a suitable size & filesystem, as shown at
<http://www.tldp.org/HOWTO/LVM-HOWTO/>. Once you're familiar with the
concepts of physical & logical extents, chapter 11 is all you'll ever
need to refer to.
- You should now be able to mount the new volume, using something like
`mount /dev/volumes/movies /mnt/temp`, so `cp -aRf
- You'll probably need to shut-down MythTV before proceeding - I always
go to a single-user runlevel - and backup & edit your /etc/fstab to
mount the /dev/volumes/movies at /path/to/movie/directory/. You'll need
to comment out the old entry for /path/to/movie/directory/ and specify
the filesystem with which you formatted the new logical volume in the
new fstab entry.
- Reboot & test.
- Provided everything has gone ok you can now add the old partition to
the logical volume group using `pvcreate` & `vgextend`. Then enlarge
the movies volume as described as
It becomes a bit more of a pain if you've currently got /etc, /lib,
/bin and suchlike in the same partition as your movies. If you have a
partition that you'll want smaller, preserving the data, you'll have to
copy everything off that partition, delete it, set up the new
partition(s) / logical volumes and then copy the data into the new
arrangement. I gather it's kinda tricky to get your root partition
itself on LVM, so I keep /etc, /lib, /bin, /sbin and so on on a
conventional partition of 6gig and then hive off only my interesting
data onto logical partitions, although experts may tune finer than
Worst case is that you currently have something like this in /etc/fstab:
# <fs> <mountpoint> <type> <opts>
/dev/hda1 /boot ext3 noauto,noatime
/dev/hda3 / reiserfs noatime
/dev/hda2 none swap sw
In this case, I'd advise booting from a liveCD to do the work - I use
the Gentoo ones. I'd mirror everything over to the new hard-drive & use
that as the new boot device - once that's working you can add the
original drive back in as secondary & add it to the logical volumes.
So fit the new hard-drive as secondary & use `fdisk` or `cfdisk` to
make a better partition layout. Don't worry about LVM just yet, just
make a big separate partition for your movies at first. Something like
100meg for /boot, 500 or 1024meg for swap, a few gig for system files
like /etc & /lib & the rest for /path/to/movie/directory/. Mark the
smallest directory as bootable & put filesystems on the partitions.
Once you've finished fdisking you'll probably need to reboot before you
can access it the new partitions.
At the liveCD shell prompt:
# mkdir /mnt/old /mnt/new
# mkdirhier /mnt/old/boot /mnt/new/boot
Mount the partions appropriately:
# mount /dev/hda3 /mnt/old
# mount /dev/hda1 /mnt/old/boot
# mount /dev/hdb3 /mnt/new
# mount /dev/hdb1 /mnt/new/boot
# mount /dev/hdb4 /mnt/new/path/to/movie/directory
Copy the files across:
# cp -Rfva /mnt/old /mnt/new
Reward yourself with a cup of tea and a cigarette whilst your drives
crunch merrily. The next thing is to do stuff with grub to make the
second drive bootable - I do this by removing the original hard-drive,
setting the new one as master, booting from a LiveCD & chrooting in
before running grub. The GRUB HOWTO is probably worth a look-see before
you start. You'll also need to edit the new drive's fstab to mount the
new /dev/hda4 as /path/to/movie/directory before you boot it. Once
you've got the new drive booting & you're sure you're happy with it all
working you can set the original drive as slave & go back to paragraph
It's all a bit time-consuming, but as long as you're clear how it all
works and you type carefully you'll be fine. When you've done this the
once you'll be plenty confident about doing it another time. Feel free
to post the output of your current `df -h` & ask for advice.
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