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On Wed, Dec 14, 2011 at 3:14 PM, Andrew Wells <agwells0714@xxxxxxxxx> wrote:

Hardware:
dd if=/dev/zero of=/data/gp/test.file bs=4096 count=1000000

4096000000 bytes (4.1 GB) copied, 4.69611 seconds, 872 MB/s

overwrite the same file:
4096000000 bytes (4.1 GB) copied, 14.5652 seconds, 281 MB/s

Virtual:
dd if=/dev/zero of=/data/gp/test.file bs=4096 count=1000000

4096000000 bytes (4.1 GB) copied, 5.6555 seconds, 724 MB/s

overwrite the same file:

4096000000 bytes (4.1 GB) copied, 6.49021 seconds, 631 MB/s

-----------------

Hardware:

dd if=/dev/zero of=/data/vol2/test.file bs=4096 count=10000000

40960000000 bytes (41 GB) copied, 46.1366 seconds, 888 MB/s

Virtual:
dd if=/dev/zero of=/data/vol2/test.file bs=4096 count=10000000

23997329408 bytes (24 GB) copied, 118.243 seconds, 203 MB/s (canceled early to get speed)

I need to get the writes to be more consistent.

On Wed, Dec 14, 2011 at 2:58 PM, John Sherwood <jrs@xxxxxx> wrote:

Use "reply all" to make sure you hit the mailing list.

The main penalty you'd hit is that if you're sharing that RAID device with any other guests (including the dom0), that can demolish your I/O speeds as it can terribly screw up what would be sequential reads. What are your benchmarks currently showing for native vs VM performance?

On Wed, Dec 14, 2011 at 2:49 PM, Andrew Wells <agwells0714@xxxxxxxxx> wrote:
it is using virtual disk (i believe a lvm partition) on local storage; local storage is over 4 or 5 raid5 devices.

The ram on the domu is 45GB

The disk I am testing is 1TB

On Wed, Dec 14, 2011 at 2:46 PM, John Sherwood <jrs@xxxxxx> wrote:
what does the config for the domU look like - are you giving it a virtual disk image stored on a local disk, using a SAN, giving it a local disk directly, etc.

On Wed, Dec 14, 2011 at 2:40 PM, Andrew Wells <agwells0714@xxxxxxxxx> wrote:

currently I am just checking and testing write performance to the disk locally on the guest

On Wed, Dec 14, 2011 at 2:33 PM, John Sherwood <jrs@xxxxxx> wrote:

that depends - what's your current bottleneck (cpu/disk/network)?

On Wed, Dec 14, 2011 at 2:26 PM, Andrew Wells <agwells0714@xxxxxxxxx> wrote:

I am using XenServer6, and I need to get performance equal or close to what we get on the hardware, especially with large files.

Are there any hints host side or guest side to increase performance. What should I look at?

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Re: [Xen-users] Disk IO tuning