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Hi!
Robin Bowes wrote:
> On Fri, June 4, 2004 7:29, Neil Brown said:
>
>> - Further support for partitionable arrays included "--auto=" option
>> and "auto=" config file entry which instructs mdadm to create the necessary
>> device files after allocating an unused array number.
>
>
> Neil,
>
> I am interpreting this to mean that I can create, for example, a large (e.g. 1TB) RAID5
> array and create smaller partitions (/home, /usr, etc) on top of the RAID5 array? Is
> this correct?
>
Hm.
Why would anyone use this, given that we can put LVM on
top of SW-RAID?
root@tolstoi:~ {593} $ vgdisplay -v
- --- Volume group ---
VG Name sys
VG Access read/write
VG Status available/resizable
VG # 0
MAX LV 256
Cur LV 8
Open LV 8
MAX LV Size 2 TB
Max PV 256
Cur PV 1
Act PV 1
VG Size 136.66 GB
PE Size 32 MB
Total PE 4373
Alloc PE / Size 4170 / 130.31 GB
Free PE / Size 203 / 6.34 GB
VG UUID 4I7XyX-nuyy-gnJY-XciQ-hlu7-Yr03-r7eoD8
- --- Logical volume ---
LV Name /dev/sys/swap1
VG Name sys
LV Write Access read/write
LV Status available
LV # 1
# open 1
LV Size 2 GB
Current LE 64
Allocated LE 64
Allocation next free
Read ahead sectors 1024
Block device 58:0
- --- Logical volume ---
LV Name /dev/sys/swap2
VG Name sys
LV Write Access read/write
LV Status available
LV # 2
# open 1
LV Size 2 GB
Current LE 64
Allocated LE 64
Allocation next free
Read ahead sectors 1024
Block device 58:1
- --- Logical volume ---
LV Name /dev/sys/root
VG Name sys
LV Write Access read/write
LV Status available
LV # 3
# open 1
LV Size 320 MB
Current LE 10
Allocated LE 10
Allocation next free
Read ahead sectors 1024
Block device 58:2
- --- Logical volume ---
LV Name /dev/sys/usr
VG Name sys
LV Write Access read/write
LV Status available
LV # 4
# open 1
LV Size 4 GB
Current LE 128
Allocated LE 128
Allocation next free
Read ahead sectors 1024
Block device 58:3
- --- Logical volume ---
LV Name /dev/sys/opt
VG Name sys
LV Write Access read/write
LV Status available
LV # 5
# open 1
LV Size 4 GB
Current LE 128
Allocated LE 128
Allocation next free
Read ahead sectors 1024
Block device 58:4
- --- Logical volume ---
LV Name /dev/sys/var
VG Name sys
LV Write Access read/write
LV Status available
LV # 6
# open 1
LV Size 4 GB
Current LE 128
Allocated LE 128
Allocation next free
Read ahead sectors 1024
Block device 58:5
- --- Logical volume ---
LV Name /dev/sys/tmp
VG Name sys
LV Write Access read/write
LV Status available
LV # 7
# open 1
LV Size 4 GB
Current LE 128
Allocated LE 128
Allocation next free
Read ahead sectors 1024
Block device 58:6
- --- Logical volume ---
LV Name /dev/sys/work
VG Name sys
LV Write Access read/write
LV Status available
LV # 8
# open 1
LV Size 110 GB
Current LE 3520
Allocated LE 3520
Allocation next free
Read ahead sectors 1024
Block device 58:7
- --- Physical volumes ---
PV Name (#) /dev/md/0 (1)
PV Status available / allocatable
Total PE / Free PE 4373 / 203
root@tolstoi:~ {595} $ mdadm --detail /dev/md/0
/dev/md/0:
Version : 00.90.00
Creation Time : Sun Feb 22 19:45:15 2004
Raid Level : raid5
Array Size : 143331712 (136.69 GiB 146.77 GB)
Device Size : 71665856 (68.35 GiB 73.39 GB)
Raid Devices : 3
Total Devices : 3
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Thu Jun 3 16:52:42 2004
State : dirty, no-errors
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
0 8 2 0 active sync /dev/scsi/host0/bus0/target0/lun0/part2
1 8 18 1 active sync /dev/scsi/host0/bus0/target1/lun0/part2
2 8 34 2 active sync /dev/scsi/host0/bus0/target2/lun0/part2
UUID : 7abbd703:643ffe8e:d6ae4d0e:1b0908aa
Events : 0.42
root@tolstoi:~ {597} $ mount
rootfs on / type rootfs (ro)
/dev/sys/root on / type reiserfs (ro)
devfs on /dev type devfs (rw)
proc on /proc type proc (rw)
/dev/sys/usr on /usr type reiserfs (ro)
/dev/sys/opt on /opt type reiserfs (ro)
/dev/sys/var on /var type reiserfs (rw,noexec)
/dev/sys/tmp on /tmp type reiserfs (rw,noexec)
/dev/sys/work on /work type reiserfs (rw,noexec)
/dev/scsi/host0/bus0/target0/lun0/part1 on /boot type ext2 (ro)
tmpfs on /dev/shm type tmpfs (rw,noexec)
What are the advantages of a partitionable md device
compared to a SWRAID+LVM configuration?
- - andreas
- --
Andreas Haumer | mailto:andreas@xxxxxxxxx
*x Software + Systeme | http://www.xss.co.at/
Karmarschgasse 51/2/20 | Tel: +43-1-6060114-0
A-1100 Vienna, Austria | Fax: +43-1-6060114-71
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