docs on storage pools?

[Richard Wurman]

So far I've been using files and/or LVM partitions for my VMs --
basically by using virt-manager and modifying existing XML configs and
just copying my VM files to be reused.

I'm wondering how KVM storage pools work -- at first I thought it was
something like KVM's version of LVM where you can just dump all your
VMs in one space .. .but it looks like it's really means different
places you want to store your VMs:

- dir: Filesystem Directory
- disk: Physical Disk Device
- fs: Pre-Formatted Block Device
- iscsi: iSCSI Target
-logical: LVM Volume Group
- netfs: Network exported directory

I understand things like LVM and storing VMs in a filesystem
directory.. but what real difference is there by going through the
GUI? I suppose nothing. Maybe I'm overthinking this -- it's just a
frontend to where you store your VMs?
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read/write performance degredation in ubuntu/debian?

[Richard Wurman]

I have run iozone on my  ubuntu 8.10 VM and it says:

random
randombkwd  record  stride
  KB  reclen   write rewritereadrereadread
writeread rewriteread   fwrite frewrite   fread  freread
4096   4   17520   49143   1194284   87115
44566   94074  50770   903871705444816  10441588611

... and that is unbearably slow. My  debian etch VM is somewhat better:

   random
randombkwd  record  stride
  KB  reclen   write rewritereadrereadread
writeread rewriteread   fwrite frewrite   fread  freread
4096   4   29559   80552   142286   144129  109956
73759  122737   86741  1148942800168013  128927   131687

..but viewing still very slow by a factor of 20, compared to my rPath
(a redhat-derived distro) 1.07 VM:

random
randombkwd  record  stride
  KB  reclen   write rewritereadrereadread
writeread rewriteread   fwrite frewrite   fread  freread
4096   4  475392  724942  1043308  1080466 1012386
768492  970375 1683570  972908   447357   693303  993935  1059245

Maybe in debian/ubuntu there is some kernel setting related to disk
I/O that I need to tweak? Anyone else seen this problem before?
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