Hi Knuth, No, in fact that's the same setup: md127 (and then md126) are the default assignments that are done by mdadm if you don't specify a specific md device.
Personally I use this in my /etc/mdadm.conf: ARRAY metadata=imsm UUID=xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx ARRAY /dev/md0 container=xxxxxxxx:xxxxxxxx:xxxxxxxx:xxxxxxxx member=0 UUID=yyyyyyyy:yyyyyyyy:yyyyyyyy:yyyyyyyy (it took me a whole evening to figure these 2 lines out) Therefore the MD device for the imsm (Intel Matrix Storage Management) container interface will be /dev/md127 (because I don't specify a specific device for it) and the MD device on top of it (the one which will be used for storage) will be /dev/md0, which is a convenient name imho. Best regards, Joël On Fri, Dec 3, 2010 at 1:31 AM, K. Posern <[email protected]> wrote: > Hi Joel, > > thanks for your answer. Because in your example you were speaking about > md0 I thought it was a somewhat different setup. > > I really like the mdadm approach that basically unmaps the fakeraid for > you via the md127 and then gives you a normal disk to play with (md126) > :) ... I don't like the naming of dmraid. > > But as you said it is handled transparently like a (true) linux software > raid --> hence you can use all the (e.g. monitoring) infrastructure of > an mdadm linux software raid :) > > Knuth > > --- > > On 12/02/2010 04:37 PM, Joël Bourquard wrote: > > 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 <[email protected] > > <mailto:[email protected]>> 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" <[email protected] > > <mailto:[email protected]> > > > <mailto:[email protected] <mailto:[email protected]>>> wrote: > > > > > > > > > > > > _______________________________________________ > > > Mailing list: > > https://launchpad.net/~sony-vaio-z-series<https://launchpad.net/%7Esony-vaio-z-series> > > <https://launchpad.net/%7Esony-vaio-z-series> > > > Post to : [email protected] > > <mailto:[email protected]> > > > Unsubscribe : > > https://launchpad.net/~sony-vaio-z-series<https://launchpad.net/%7Esony-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> > > <https://launchpad.net/%7Esony-vaio-z-series> > > Post to : [email protected] > > <mailto:[email protected]> > > Unsubscribe : > > https://launchpad.net/~sony-vaio-z-series<https://launchpad.net/%7Esony-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 Post to : [email protected] Unsubscribe : https://launchpad.net/~sony-vaio-z-series More help : https://help.launchpad.net/ListHelp
