[linux-lvm] LVM performance

[Volker Jahns]

Bradley M Alexander wrote:
> 
> Hi all,
> 
> All right. I've got LVM installed and running on 2 30GB IDE drives, a VG on
> each, and the partitions divided just about evenly between them. This is on
> a 1GHz Athlon with 640MB of RAM. I am running Debian/sid with lvm 1.0.1rc4
> and kernel 2.4.13.
> 
> A few things I have noticed in the week or so that I have been using LVM.
> First, the drive activity light stays lit all the time. I'm not terribly
> worried about it, since things seem to be behaving normally, but I figured
> I would ask.
> 
> The second, and far more disturbing thing is that any heavy accesses to the
> filesystem (copying large files, scp-ing files mastering CDs, anything with
> a lot of IO brings my machine to its knees. Case in point. When I started
> this message, I was mastering a CD using xcdroast, which had called
> mkisofs. Not only did the mastering take (I'm guessing here, since I didn't
> note the time) about 10 minutes, the load average jumped, at one point, to
> 8.23, and generally hovered around the 6-to-7 range. Copying large files
> from filesystem to filesystem on the machine yields similar results.
> Originally, I had the following configuration:
> 
> hda 30GB HD
> hdb 30GB HD
> hdc DVD-ROM
> hdd CD-RW
> 
> A friend suggested moving the HD on hdb to the other channel, so now the
> drives are on hda and hdc, the dvd is on hdb and the cdrw is on hdd.
> 
> Can anyone give me any ideas as to why the machine gets beaten about so
> much during IO operations and more importantly how can I minimize the
> impact.
> 
> Regards,
> --
> --Brad
> ============================================================================
> Bradley M. Alexander, CISSP              |   Co-Chairman,
> Beowulf System Admin/Security Specialist |    NoVALUG/DCLUG Security SIG
> Debian/GNU Linux Developer               |   storm at debian.org
>                                          |   storm at tux.org
> ============================================================================
> Never sign a contract which contains the phrases "sort of," "kind of," or
> "and stuff."
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm at sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://www.sistina.com/lvm/Pages/howto.html

There is an article in iX (http://www.heise.de/ix) about performance
issues
w/ LVM or VINUM (it is written in German, though). 

                      1. Christoph Herrmann: (avr)
                      Scheibenweise
                      FreeBSDs Vinum und Linux' LVM im Vergleich
                      review
                      iX 9/01, Seite 68

You might check w/ this.

Also, why don't you use a "cheap" raid controller which will do the
homework for you in hardware _not_ software?

Regards
-- 
Volker Jahns, Volker.Jahns at thalreit.de, http://thalreit.de