From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: convert raid10 to raid0 Date: Thu, 8 Jul 2010 08:50:34 +1000 Message-ID: <20100708085034.2bc8272e@notabene.brown> References: <4C34D5AD.5020305@i3rendszerhaz.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <4C34D5AD.5020305@i3rendszerhaz.hu> Sender: linux-raid-owner@vger.kernel.org To: =?UTF-8?B?VMOzdGg=?= Csaba Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Wed, 07 Jul 2010 21:29:49 +0200 T=C3=B3th Csaba wrote: > Hey List, >=20 > i have a serious problem: have a file server with 4 disk (4x750GB), > using them in a software RAID10 array. One of the HDDs have a bad sec= tor > (because some administration problems, i cannot replace them), and th= e > motherboard sometimes drops the connection with two HDDs. Not with th= e > same as the bad sector has, but with a resync i always managed the > problem. But now 3 drive form the RAID10 array dropped. >=20 > In the past the sdc6 and the sdd6 partitions were the partitions i > resynced the others, so i know exactly where to look for the proper > datas. Can i use them as a RAID0 array somehow? It should be sufficient to: mdadm -S /dev/md5 mdadm -C /dev/md5 --level raid0 --raid-devices 2 --chunk 512 \ --metadata=3D1.1 /dev/sdc6 /dev/sdd6 to get your data available. There is a possible small complication though. If you use a different version of mdadm to the one you used to create the array at first, it m= ight choose a different 'data offset'. To be sure this doesn't happen, use mdadm -E /dev/sdc6 and take note of the "Data Offset". It would probably be a good idea t= o keep a copy of "mdadm -E" of all of the devices, just to be on the same side= =2E Then after you create the raid0, use the same command mdadm -E /dev/sdc6 to check the Data Offset again and make sure it is the same. I suspect it will be, so everything will be fine. However if it isn't don't try to access the array. Post the details a= nd I'll figure out what to do next. NeilBrown > In past mdadm warning letters i saw the config: >=20 > Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] > [raid4] [multipath] [faulty] > md5 : active raid10 sdc6[0] sdd6[3] sdb6[1](F) sda6[2](F) > 1434619904 blocks super 1.1 512K chunks 2 near-copies [4/2] [U_= _U] >=20 > md1 : active raid1 sdb5[0] sdc5[1] > 14763635 blocks super 1.1 [2/2] [UU] >=20 > md0 : active raid1 sdd5[0] sda5[2](F) > 14659200 blocks [2/1] [U_] >=20 > unused devices: >=20 >=20 > Now i have: >=20 > minerva ~ # cat /proc/mdstat > Personalities : [linear] [raid0] [raid1] [raid10] [raid6] [raid5] > [raid4] [multipath] [faulty] > md5 : inactive sdd6[3] > 717310119 blocks super 1.1 >=20 > md1 : active raid1 sdc5[0] sdb5[1] > 14763635 blocks super 1.1 [2/2] [UU] >=20 > md0 : active raid1 sda5[1] sdd5[0] > 14659200 blocks [2/2] [UU] >=20 > unused devices: > minerva ~ # mdadm --detail /dev/md5 > /dev/md5: > Version : 1.1 > Creation Time : Thu Nov 26 14:50:07 2009 > Raid Level : raid10 > Used Dev Size : 717309952 (684.08 GiB 734.53 GB) > Raid Devices : 4 > Total Devices : 1 > Persistence : Superblock is persistent >=20 > Update Time : Wed Jul 7 10:34:32 2010 > State : active, FAILED, Not Started > Active Devices : 1 > Working Devices : 1 > Failed Devices : 0 > Spare Devices : 0 >=20 > Layout : near=3D2 > Chunk Size : 512K >=20 > Name : minerva:5 (local to host minerva) > UUID : a73f5902:accc2488:aecfdc14:05a6e2f4 > Events : 3981420 >=20 > Number Major Minor RaidDevice State > 0 0 0 0 removed > 1 0 0 1 removed > 2 0 0 2 removed > 3 8 54 3 active sync /dev/sdd6 >=20 >=20 >=20 >=20 > If i try to add sdc6 to the md5 array it fails, because it tries to a= dd > as a fifth device: >=20 > minerva ~ # mdadm /dev/md5 -a /dev/sdc6 > mdadm: add new device failed for /dev/sdc6 as 4: Invalid argument >=20 >=20 >=20 > Please help, i don't want to destroy the datas, and i have never job > with RAID10 under linux. >=20 > thanks in advance, > regards, > Csaba > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid"= in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html