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Re: [Xen-users] very slow disk access

On Sun, Feb 27, 2011 at 8:16 AM, Randy Katz <rkatz@xxxxxxxxxxxxxxxxxxxxx> wrote:
> On 2/26/2011 4:41 PM, Fajar A. Nugraha wrote:
>> On Sat, Feb 26, 2011 at 11:20 PM, Randy Katz
>> <rkatz@xxxxxxxxxxxxxxxxxxxxx>  wrote:
>>> # lsmod | egrep "piix|hci"
>>> ahci                   69705  7
>>> ata1: SATA max UDMA/133 abar m2048@0xff970000 port 0xff970100 irq 253
>>> ata1.00: ATA-8: ST31500341AS, CC1H, max UDMA/133
>>> ata1.00: configured for UDMA/133
>> A quick glance seems to show no driver problems. Did you experience
>> any problem? Is your problem xen-specific?
> I have very slow access in Xen for file based access. If I use LVM volumes
> it is quite fast.

Then why didn't you say so in the first post? It shouldn't be related
to drivers. using file-based images are known to be slow or unreliable
in some circumstances.

> Using the same machine with OpenVZ
> has no problems and performance is great.

OpenVZ has different method to provide guest filesystem.

> Will go ahead and use LVM volumes
> and assume Xen likes them! :) Not sure what
> else to do or look at, any comments?

If you still need file-based image, try using non-sparse image and use
tap:aio instead of file:/
Stick with LVs whenever you can though.


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