Best practice for guest disk

SUSE Product Topics SLES Virtualization
1

Hi all,

this might not be the right forum, but I’ll give it a try:

  • I am on SLES11, sp3
  • XEN hypervisor
  • HP380 hardware

For my DomU’s I normally create partitions on Dom0 (on underlying raid5) and use that for DomU disks
The alternative is files directly on DomO

What is the better and preferred way? and why?
Any performance considerations? (I am quite satisfied)

Best regards
Claus, DK

2

Hi Claus,

[QUOTE=clausbc;22949]Hi all,

this might not be the right forum, but I’ll give it a try:

  • I am on SLES11, sp3
  • XEN hypervisor
  • HP380 hardware

For my DomU’s I normally create partitions on Dom0 (on underlying raid5) and use that for DomU disks
The alternative is files directly on DomO

What is the better and preferred way? and why?
Any performance considerations? (I am quite satisfied)

Best regards
Claus, DK[/QUOTE]

I prefer SAN storage - per NPIV, per DomU :wink:

Using block storage (partitions or LVM LVs) vs. file storage (disk image files on some Dom0 file system) IMO depends:

  • block storage is typically less flexible than file storage (changing partitions is more interruptive than creating new files)
  • file storage has more overhead (writes have to go through the Dom0 file system)
  • block storage interferes less with Dom0 file system activity (only at the device level, and only if you need to share the same disk device or HBA (i.e. a single SCSI adapter)
  • file storage can make use of excess RAM at Dom0 level, as a write cache
  • clustering block storage may be easier and more performing than clustering file storage

So it depends on a number of factors. Generally, I’d try to separate Dom0 and DomU storage as much as I can: separate disks and even controllers, if possible. Once clustering comes into play, I’d look for SAN (FC / iSCSI) solutions, rather than using native Dom0 storage.

Just my opinion, of course…

Regards,
Jens