LVM *was* Re: [mythtv-users] Highest number of simultaneous streams recorded?

Brandon Beattie brandon+myth at
Fri Oct 14 16:13:33 EDT 2005

On Fri, Oct 14, 2005 at 03:11:42PM -0400, Steve Adeff wrote:
> > > another option if you find yourself recording this much is to use LVM
> > > (logical
> > > volume manager). It would allow you to connect, say four 300gig drives
> > > and use them all as one AND stripe data across them (like RAID 0). Or you
> > > could
> > > use 3 striped and the 4th as a parity drive in case one dies.
> > > This would most definitely give you the drive speed required to not only
> > > record 4+ streams at once, but play back equally as many.
> > >
> > >
> > > Steve
> from my understanding, yes it is, and properly set up you can also add and 
> remove drives from an LVM at any point as well. I recently discovered LVM so 
> I've yet to implement it, but I did a good amount of research and it seems to 
> be quite easy now and I did not see anything that made me think I'd have to 
> reinstall. Of course, I wouldn't use a LVM for your root partition, at least 
> until you know what your doing... I'm just going to be using it for my 
> storage drives.

Before you go running off let me give you a warning.  Although LVM
supports striping, adding/removing disks, shrinking and growing fs's,
they do _not_ all work together.  If you stripe you can't add/remove
disks or change fs size.  If you use xfs or jfs you can't shrink a
fs.  After using Raid 0, 1, 5, LVM on 6 disks with XFS, JFS, and Reiser
I have settled with only LVM and ReiserFS (As much as I dislike Reiser
for performance downsides with many gig files compared to xfs and jfs).
In my experience, raid 5 is overkill for my desire to record TV shows.
Anything I want safe I backup to another computer completely.  In
dealing with 6 drives I've found it very useful to shrink fs's at times,
and since ReiserFS (Not Reiser 4) is the only fs that supports shrinking
I use it.  Striping would be nice, but adding/removing disks I've found
to be a much better feature.

I've also found seagate drives to run 10%-30% faster for reading and
writing (reading and writing 100+ gig files) plus the 5yr warranty comes
in nice, since of 9 drives I've had in the last 3 years, half the Maxtor
200GB drives have gone bad.

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