sony-vaio-z-series team mailing list archive

[Joël Bourquard <joel.bourquard@xxxxxxxxx>]

Hi Knuth !

Well actually I believe you have exactly the same setup as me.  And it *is*
a linux software raid - it just happens to be setup with the parameters read
from the Intel fakeraid metadata that is on the disks. But the operation is
fully software.

/dev/md126 is the linux software raid, which uses /dev/md127 as the
underlying interface to the metadata.  You can see that in /proc/mdstat:

md127 : inactive sdd[3](S) sda[2](S) sdb[1](S) sdc[0](S)
      9028 blocks super external:imsm

But /dev/md126 is really a true linux software raid0, with a 128kB stripe
size.

Yes, many distros (including Gentoo also) still use initrd's which don't
include mdadm 3.0+, which is required to handle the intel metadata. That's
why I recommend to copy a static compile of it, to the initrd.

Best regards,

Joël


On Thu, Dec 2, 2010 at 9:31 PM, K. Posern <quickhelp@xxxxxxxxx> wrote:

>
> Hi Joel,
>
> Thanks for the report.
>
> I ca add though:
>
> If you use mdadm instead dmraid to access your NATIVE fakeraid (without
> a linux software raid) you get actually the same results :)
>
> hdparm -tT /dev/md0
>
> /dev/md126:
>  Timing cached reads:   9010 MB in  2.00 seconds = 4506.74 MB/sec
>  Timing buffered disk reads: 1498 MB in  3.00 seconds = 498.81 MB/sec
>
> And a little side remark:
>
> For all I know: mdadm is also favored by intel going forward over dmraid
> - but ubuntu still favors dmraid by default (I think).
>
> Best,
>
> Knuth
>
> On 12/02/2010 12:42 PM, Joël Bourquard wrote:
> > Actually I think buffered reads are the same, it's just some measurement
> > variance that we see here :-)
> >
> > I noticed a major improvement when launching huge apps (firefox,
> > evolution, OpenOffice) for the first time, and of course when copying
> files.
> >
> > Other than that, the general speed of the system was already very high -
> > so it's difficult to rule out the placebo effect. But it's certainly not
> > running any slower than before, far from it! And numbers are consistent.
> >
> > Best regards,
> >
> > Joël
> >
> > --
> > Sent from my Android phone.
> > Please excuse my brevity.
> >
> > On Dec 2, 2010 6:31 PM, "Simon Brown" <lists@xxxxxxxx
> > <mailto:lists@xxxxxxxx>> wrote:
> >
> >
> >
> > _______________________________________________
> > Mailing list: https://launchpad.net/~sony-vaio-z-series<https://launchpad.net/%7Esony-vaio-z-series>
> > Post to     : sony-vaio-z-series@xxxxxxxxxxxxxxxxxxx
> > Unsubscribe : https://launchpad.net/~sony-vaio-z-series<https://launchpad.net/%7Esony-vaio-z-series>
> > More help   : https://help.launchpad.net/ListHelp
>
>
>
> _______________________________________________
> Mailing list: https://launchpad.net/~sony-vaio-z-series<https://launchpad.net/%7Esony-vaio-z-series>
> Post to     : sony-vaio-z-series@xxxxxxxxxxxxxxxxxxx
> Unsubscribe : https://launchpad.net/~sony-vaio-z-series<https://launchpad.net/%7Esony-vaio-z-series>
> More help   : https://help.launchpad.net/ListHelp
>
>