Re: Couple of quetsions HD perf, mac address...

[Laurent Vivier <Laurent.Vivier-6ktuUTfB/bM@public.gmane.org>]

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Benjamin Budts wrote:
[snip]
> 1* When i run hdparm -t /dev/sda1 I have 80-85Mbit/s read speed on my 
> guest os (debian etch)
> 
> If I run it ''in'' a virtual machine (using also debian Etch with 
> 2.6.21.5 kernel) I get : 28-35Mbits...
> 
> I even tried to put the image on a seperate disk to be able to have 
> more, but I can't get more then 35Mbits out of it...
> 
> How can I up the disk performance without having to replace everything 
> by SCSI hardware ?
> 

You can improve performance by using virtual SCSI disks. I post some
benchchmarks with dbench on this list at the end of may (24/05).

QEmu (and thus KVM) doesn't support natively SCSI disk for the PC virtual
machine. I post a patch the 1st of march on QEmu mailing list to add a "-sda"
parameter to use SCSI disk (but my approach was not approved by maintainers).
The problem with the virtual SCSI is you cannot boot on it because there is no
BIOS to manage it. But you can use it as storage and boot linux using the
parameter "-kernel" to load directly the kernel from the host disk.

Regards,
Laurent
-- 
------------- Laurent.Vivier-6ktuUTfB/bM@public.gmane.org  --------------
       "Any sufficiently advanced technology is
  indistinguishable from magic." - Arthur C. Clarke


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