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> > > Post to : [email protected] > <mailto:[email protected]> > > 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 : [email protected] > <mailto:[email protected]> > Unsubscribe : https://launchpad.net/~sony-vaio-z-series > <https://launchpad.net/%7Esony-vaio-z-series> > More help : https://help.launchpad.net/ListHelp > >
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