On Sun, 30 May 2010 18:29:16 -0500 "Leslie Rhorer" <lrhorer@xxxxxxxxxxx> wrote: > > Am I confused about reshaping a RAID5 to RAID6 array, or is there an > error in the man page? The distro I have on one of my servers - Debian > "Squeeze" - employs mdadm 3.0.3, internally dated Oct. 22, 2009. The man > page that comes with the software specifically says: > > -l, --level= > > <snip> > > Not yet supported with --grow. Man page is wrong. Thanks for reporting. Fixed in current .git and will be in next release. > > Searching the web, however, I find the following link from Aug. 17, > 2009: > > http://neil.brown.name/blog/20090817000931 > > In the link, it says: > > Now, in mid 2009, we have most of the rest of the reshaping options that had > been planned. These include changing the stripe size, changing the layout > (i.e. where the parity blocks get stored) and reducing the number of > devices. > > Changing the layout provides valuable functionality as it is an important > part of converting a RAID5 to a RAID6. > > <snip> > > Currently supported reshapes > > <snip> > > RAID5 > A RAID5 can change the number of devices, the size of the individual > devices, the chunk size and the layout. A 2 drive RAID5 can be converted to > RAID1, and a 3 or more drive RAID5 can be converted to RAID6. > > Since the 3.0.3 version of mdadm was evidently written in October, > and since this link was from August, one would think 3.0.3 should be able to > re-shape a RAID5 to RAID6. If so, the man page (at least for Debian > "Squeeze") is incorrect, and of course fails to offer the syntax for such an > upgrade. > > Am I missing something? The syntax for changing levels is simply: mdadm --grow /dev/mdX --level=6 This will preserve the number of data disks. If you want to change that (or anything else) at the same time, you can: mdadm --grow /dev/mdX --level=6 --raid-disk=8 --chunk-size=1024 --layout=left-asymetric Thanks, NeilBrown > > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
