Re: [Xen-users] creating domU's consumes 100% of system resources

[n8&abby <thoughtobject@xxxxxxxxx>]

Thanks for your response William,

I have 8x 750GB 7200rpm SAMSUNG HD753LJ SATA Drives using a 3ware 9650SE hardware raid controller.  These 8 disks are configured using raid 5 and are collected together into a single "unit" of about 4.77TB.  The card then presents this array to look like 2 disks.  Dom0 (Debian Etch amd64) is installed on the 3GB /dev/sda and is limited to 1024MB ram.  The other 15Gigs of memory on the server are for the domU's.  The server has 1x quad core amd64 2Ghz processor.

# fdisk -l /dev/sda
Disk /dev/sda: 3221 MB, 3221224960 bytes
255 heads, 63 sectors/track, 391 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1             329         391      506047+   5  Extended
/dev/sda2   *           1         328     2634628+  83  Linux
/dev/sda5             330         391      498015   82  Linux swap / Solaris
Partition table entries are not in disk order

Data and domU's are installed on an LVM volume on /dev/sdb

# fdisk -l /dev/sdb
Disk /dev/sdb: 5246.6 GB, 5246699962880 bytes
255 heads, 63 sectors/track, 637874 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk /dev/sdb doesn't contain a valid partition table



The 3ware raid card comes with a great web based interface and all drives check out great.

Here are results from bonnie while only one domU was running.  This domU was serving a couple bittorents at about 250kB/s before running the bonnie test.  While running this test, the domU machine became almost completely
unresponsive and was only able to serve at a speed of about 10kB/s.

# bonnie++ -s 2048 -d /mnt/domU/tmp -u root

Version  1.03       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
dom0             2G  5065  13  5095   1  3668   0 32225  74 205758   3 389.5   0
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++

Here is the same test without any running domU's.

# bonnie++ -s 2048 -d /mnt/seed/tmp -u root
Version  1.03       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
sbh2             2G  5320  13  5365   1  3931   0 34210  70 247347   4 513.2   0
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
                 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++

I would appreciate ideas anyone has about this.

Thanks,
-=nathan

How are your disks set up? RAID 0, 1, 5, 10, or 50? What speed disks?

Any number of things could be causing this, but I would check your
storage situation first, as a failing disk could be very problematic.

William

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