[mythtv-users] OT: new to logical volumes and LVM

R. G. Newbury newbury at mandamus.org
Wed Dec 5 14:36:48 UTC 2007

> Marc Barrett wrote:
>> I have two partitions which I would like to logically join so I can
>> use them as a single directory, mounted as /myth.  I have a lot
>> of experience with partitioning hard drives and such under Linux,
>> but I am fairly new to logical drives and LVM, especially under
>> Linux.  
>> My setup is a knoppmyth system, which automatically configured
>> my main drive hda as three partitions, for root, swap, and /myth.
>> I also have a second hard drive in the system, which has a
>> Windows installation on it.  I used a Linux utility to shrink the
>> NTFS partition, which resulted in a second partition on that drive,
>> which I formatted as ext3.  To make a long story short, I would
>> like to logically join hda3 and hdb2 as a single logical partition,
>> and mount it as /myth so my existing knoppmyth setup can use
>> it for recordings.  I would appreciate it if someone could give
>> me some tips on how to do this.

ISTR that Storage Directories had been ported from SVN into trunk. If 
you have an item "6. Storage Directories" in mythtv-setup you do not 
need to touch RAID or LVM. Just give your new disk a mount point in your 
system ( "/video2" for example ) and mythtv is good to go. Myth 
thereafter takes care of all the backend details of storage. It searches 
for files in the storage directories list.

Advantages: You can add ( or remove) disks without difficulty. To 
remove, just move the files to other disks, until there are no myth 
files left, shutdown and remove.

If a disk fails, you only lose the files on that disk.

Works for NFS mounts too, if you have physical disk limits while 
swapping disks.

You can re-size (Qparted etc.) to your heart's content.

Disadvantages: If a disk fails you lose the files on that disk and have 
to hunt through 'Watch Recordings' list to see what you lost, and delete 
them from the system from there. A RAID setup will avoid this. AIUI LVM 
will not and may lose you everything...I may have that wrong about that, 
but I stay well away from LVM. I consider RAID is overkill for myth 
usage...it's only TV shows afterall...your comfort level may vary.

My myth setup uses 3 disks: one IDE for the system, (13Gig) and 2 SATA 
for video (100 and 250 Gig raw).



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