On Thu, 19 Jul 2012 15:11:06 +0800 Zhang Jiejing <b33651@xxxxxxxxxxxxx> wrote: > Hi Neil Brown, > > Sorry for interrupt you. > > I'm using linux md raid0 in my server, and it's working very good unless > it's outof space recently. > Thanks for you good job. > > I have two question about linux md, > 1. the first one maybe a common one: > I install my server /home dir as RAID-0 for speed, this server is > usually to code build and development, but recently I need add a 2TB HDD > to this md, and I found add disk on RAID-0 is not supported, but I found > there will maybe a way to convert my RAID-0 to RAID-5, and then add > other disk on the RAID-5 (I don't covert it back). > > I sow some patch about md takeover: > like > md/raid4: permit raid0 takeover > md: Fix dev_sectors on takeover from raid0 to raid4/5 > > But I'm a newbie about linux md, can you give a some guide about how to > do this or it was not supported ? If you use a recent kernel (3.4) and a recent mdadm you should be able to grow a RAID0 array. It will be converted to RAID5, reshaped, then converted back. I recommend creating some 'loopback' devices to experiment with just to make sure it works. i.e. create 4 big files, use "losetup /dev/loop0 filename" etc to create 4 loopback devices. Create a RAID0 over 3 of those, then try to add a device. The command is: mdadm --grow /dev/md0 --raid-devices=4 --add /dev/loop3 or similar. > > My kernel version: Linux 2.6.38-15-server #64-Ubuntu SMP Fri Jul 6 > 19:08:52 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux > > mdadm - v3.1.4 - 31st August 2010 You'll definitely need newer kernel and mdadm. > > > 2. the second question is about radi0.c : create_strip_zones() function, > this function will scan mddev->disks and check them EQUAL size or not, > can you give me some guide about where this disks passed to this mddev ? > > The reason I ask this question is, I add a new HD, and partition two > "Linux raid autodetect" partition on this disk, but I don't know how to > add this disk to md1. > > So I type: > mdadm --add /dev/md1 /dev/sdc > and report -EINVAL error. You cannot add a device to a RAID0 - there is nowhere to put it. To grow a RAID0, you give the --add in the same command as the --grow, as above. > > I first tough is I caused by my partition not right, so I partition my > sdc to 2 partition, with partition type is "Linux raid autodetect". > > and found also failed, so I did some google, and found RAID-0 don't > support add disk online. > > After did a ubuntu "do-release-upgrade", and reboot, I found kernel will > check /dev/sdc, looking at sdc, and then failed to create the zone. > > After remove the HD in BIOS, I can success mount the md1 again, so my > question is do I need do some mdadm command to remove the /dev/sdc in my > md1 (maybe it record the device node in some where ?) > > > Thanks for you advance. > NeilBrown
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