From mboxrd@z Thu Jan 1 00:00:00 1970 From: maarten Subject: Re: Spares and partitioning huge disks Date: Sat, 8 Jan 2005 20:01:09 +0100 Message-ID: <200501082001.09317.maarten@ultratux.net> References: <20050108145228.GB26475@janus> <200501081749.32816.maarten@ultratux.net> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200501081749.32816.maarten@ultratux.net> Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Saturday 08 January 2005 17:49, maarten wrote: > On Saturday 08 January 2005 15:52, Frank van Maarseveen wrote: > > On Fri, Jan 07, 2005 at 04:57:35PM -0500, Guy wrote: > > > His plan is to split the disks into 6 partitions. > > > Each of his six RAID5 arrays will only use 1 partition of each physical > > > disk. > > > If he were to lose a disk, all 6 RAID5 arrays would only see 1 failed > > > disk. If he gets 2 read errors, on different disks, at the same time, > > > he has a 1/6 chance they would be in the same array (which would be > > > bad). His plan is to combine the 6 arrays with LVM or a linear array. > > > > Intriguing setup. Do you think this actually improves the reliability > > with respect to disk failure compared to creating just one large RAID5 > > array? As the system is now online again, busy copying, I can show the exact config: dozer:~ # fdisk -l /dev/hde Disk /dev/hde: 250.0 GB, 250059350016 bytes 255 heads, 63 sectors/track, 30401 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/hde1 1 268 2152678+ fd Linux raid autodetect /dev/hde2 269 331 506047+ fd Linux raid autodetect /dev/hde3 332 575 1959930 fd Linux raid autodetect /dev/hde4 576 30401 239577345 5 Extended /dev/hde5 576 5439 39070048+ fd Linux raid autodetect /dev/hde6 5440 10303 39070048+ fd Linux raid autodetect /dev/hde7 10304 15167 39070048+ fd Linux raid autodetect /dev/hde8 15168 20031 39070048+ fd Linux raid autodetect /dev/hde9 20032 24895 39070048+ fd Linux raid autodetect /dev/hde10 24896 29759 39070048+ fd Linux raid autodetect /dev/hde11 29760 30401 5156833+ 83 Linux dozer:~ # cat /proc/mdstat Personalities : [linear] [raid0] [raid1] [raid5] [multipath] read_ahead 1024 sectors md1 : active raid1 hdg2[1] hde2[0] 505920 blocks [2/2] [UU] md0 : active raid1 hdg1[1] hde1[0] 2152576 blocks [4/2] [UU__] md2 : active raid1 sdb2[0] sda2[1] 505920 blocks [2/2] [UU] md3 : active raid5 sdb5[2] sda5[3] hdg5[1] hde5[0] 117209856 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] md4 : active raid5 sdb6[2] sda6[3] hdg6[1] hde6[0] 117209856 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] md5 : active raid5 sdb7[2] sda7[3] hdg7[1] hde7[0] 117209856 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] md6 : active raid5 sdb8[2] sda8[3] hdg8[1] hde8[0] 117209856 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] md7 : active raid5 sdb9[2] sda9[3] hdg9[1] hde9[0] 117209856 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] md8 : active raid5 sdb10[2] sda10[3] hdg10[1] hde10[0] 117209856 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] # Where md0 is "/" (temporary degraded), and md1 and md2 are swap. # The md3 through md8 are the big arrays that are part of LVM. dozer:~ # pvscan pvscan -- reading all physical volumes (this may take a while...) pvscan -- ACTIVE PV "/dev/md3" of VG "lvm_video" [111.72 GB / 0 free] pvscan -- ACTIVE PV "/dev/md4" of VG "lvm_video" [111.72 GB / 0 free] pvscan -- ACTIVE PV "/dev/md5" of VG "lvm_video" [111.72 GB / 0 free] pvscan -- ACTIVE PV "/dev/md6" of VG "lvm_video" [111.72 GB / 0 free] pvscan -- ACTIVE PV "/dev/md7" of VG "lvm_video" [111.72 GB / 0 free] pvscan -- ACTIVE PV "/dev/md8" of VG "lvm_video" [111.72 GB / 0 free] pvscan -- total: 6 [670.68 GB] / in use: 6 [670.68 GB] / in no VG: 0 [0] dozer:~ # vgdisplay --- Volume group --- VG Name lvm_video VG Access read/write VG Status available/resizable VG # 0 MAX LV 256 Cur LV 1 Open LV 1 MAX LV Size 2 TB Max PV 256 Cur PV 6 Act PV 6 VG Size 670.31 GB PE Size 32 MB Total PE 21450 Alloc PE / Size 21450 / 670.31 GB Free PE / Size 0 / 0 VG UUID F0EF61-uu4P-cnCq-6oQ6-CO5n-NE9g-5xjdTE dozer:~ # df Filesystem 1K-blocks Used Available Use% Mounted on /dev/md0 1953344 1877604 75740 97% / /dev/lvm_video/mythtv 702742528 42549352 660193176 7% /mnt/store # As of yet there are no spares. This is a todo, the most important thing is to get the app back in working state now. I'll probably make a /usr md device in future from hdX3, as "/" is completely full. This was because of legacy constraints, migrating drives... Maarten