Re: Xen Dom0 vs. DomU disk I/O

[eric%cirr.com@localhost (Eric Schnoebelen)]

Stephan writes:
- It would be nice if anyone could provide some data from a NetBSD dom0
- instead of a Linux one.

From my XEN server (A Sun X2200M2):

  atlantis-> uname -a
  NetBSD atlantis.cirr.com 5.99.58 NetBSD 5.99.58 (XEN3_DOM0) #3: Sat Dec 10 
04:04:22 CST 2011 
eric%bob-the-builder.cirr.com@localhost:/work/eric/NetBSD-current/obj/amd64/sys/arch/amd64/compile/XEN3_DOM0
 amd64
  atlantis-> dd if=/dev/zero of=t bs=64k count=1000
  1000+0 records in
  1000+0 records out
  65536000 bytes transferred in 1.338 secs (48980568 bytes/sec)

And one of the VM's on that box:

  egsner-> uname -a
  NetBSD egsner.cirr.com 6.0_STABLE NetBSD 6.0_STABLE (XEN3_DOMU) #11: Tue Nov 
13 23:27:04 CST 2012 
eric%bob-the-builder.cirr.com@localhost:/work/eric/NetBSD-6/obj/amd64/sys/arch/amd64/compile/XEN3_DOMU
 amd64
  egsner-> dd if=/dev/zero of=t bs=64k count=1000
  1000+0 records in
  1000+0 records out
  65536000 bytes transferred in 5.713 secs (11471381 bytes/sec)


Background information:

atlantis has two 3TB SATA drives, about 7200 rpm as I recall

  wd0 at atabus1 drive 0
  wd0: <Hitachi HDS723030ALA640>
  wd0: drive supports 16-sector PIO transfers, LBA48 addressing
  wd0: 2794 GB, 5814021 cyl, 16 head, 63 sec, 512 bytes/sect x 5860533168 
sectors
  [...]
  wd1 at atabus2 drive 0
  wd1: <Hitachi HDS723030ALA640>
  wd1: drive supports 16-sector PIO transfers, LBA48 addressing
  wd1: 2794 GB, 5814021 cyl, 16 head, 63 sec, 512 bytes/sect x 5860533168 
sectors

The drives are partitioned using GPT.  atlantis has it's
filesystems in a 21037056 sector GPT slice, one on each drive,
mirrored together using raidframe.

Each of the VM's on atlantis are also created out of mirrored
slices, using raidframe on the Dom0. (all the mirroring overhead
is in the Dom0 rather than in the DomU.)

I don't have any Linux VM's on that Dom0, so I can't give
comparable rates through the Linux IO subsystem.

--
Eric Schnoebelen                eric%cirr.com@localhost         
http://www.cirr.com
  Vampireware; n, a project capable of sucking the lifeblood out of anyone
      unfortunate enough to be assigned to it, which never actually sees 
      the light of day, but nonetheless refuses to die. -- 
tlode%nyx.net@localhost