vm-install: tap:aio instead of file

Hi,

according to the docs file backed virtual block devices
should be 
avoided, if heavy IO may occur. Use never sparse files here
- so I read 
on xen-users and: tap:aio should be preferred in such
cases.

My question: Can this be done with vm-install ?

If yes, how ?

If no, how can it be done manually (I tried, replacing file
with tap:aoi 
in a working configuration - boot froze) ?

Kind regards

Gerd

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On Fri, Jul 27, 2007 at  9:46 AM, Gerd Bavendiek
<gerd.bavendiekgmx.net> wrote: 
> Hi,
> 
> according to the docs file backed virtual block devices
should be 
> avoided, if heavy IO may occur. Use never sparse files
here - so I read 
> on xen-users and: tap:aio should be preferred in such
cases.
> 
> My question: Can this be done with vm-install ?

Not in SLES 10 SP1 or older.  Due to bugs in xend, this was
not reliable, so I didn't put support in vm-install.

I am currently trying to make this work in openSUSE 10.3. 
vm-install has support for this in 10.3, but xend still has
some problems.


> If yes, how ?
> 
> If no, how can it be done manually (I tried, replacing
file with tap:aoi 
> in a working configuration - boot froze) ?

On the latest openSUSE 10.3 alpha, you can specify the
source of your disks using the same prefixes that Xen uses
(so, "tap:aio:/var/lib/xen/images/vmname/disk0",
or even
"tap:qcow:/var/lib/xen/images/vmname/disk0").

Note that xend still has trouble booting from such a disk. 
This should be fixed by beta 1.


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Thanks, Charles.

So for SLES10 I have to wait for SP2 ?

Gerd

Charles Coffing schrieb:
> On Fri, Jul 27, 2007 at  9:46 AM, Gerd Bavendiek
<gerd.bavendiekgmx.net> wrote: 
>> Hi,
>>
>> according to the docs file backed virtual block
devices should be 
>> avoided, if heavy IO may occur. Use never sparse
files here - so I read 
>> on xen-users and: tap:aio should be preferred in
such cases.
>>
>> My question: Can this be done with vm-install ?
> 
> Not in SLES 10 SP1 or older.  Due to bugs in xend, this
was not reliable, so I didn't put support in vm-install.
> 
> I am currently trying to make this work in openSUSE
10.3.  vm-install has support for this in 10.3, but xend
still has some problems.
> 
> 
>> If yes, how ?
>>
>> If no, how can it be done manually (I tried,
replacing file with tap:aoi 
>> in a working configuration - boot froze) ?
> 
> On the latest openSUSE 10.3 alpha, you can specify the
source of your disks using the same prefixes that Xen uses
(so, "tap:aio:/var/lib/xen/images/vmname/disk0",
or even
"tap:qcow:/var/lib/xen/images/vmname/disk0").
> 
> Note that xend still has trouble booting from such a
disk.  This should be fixed by beta 1.
> 
> 

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On Fri, Jul 27, 2007 at 10:15 AM, Gerd Bavendiek
<gerd.bavendiekgmx.net> wrote: 
> Thanks, Charles.
> 
> So for SLES10 I have to wait for SP2 ?

More likely the second Xen maintenance update for SP1.  I'm
targeting a set of vm-install fixes for the next update.

(First update is moving through testing and into the channel
now.)


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