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
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