From: Robin Bowes <hidden> Date: 2004-06-04 10:12:33
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?
Where can I read more about this?
Thanks,
R.
--
http://robinbowes.com
From: Andreas Haumer <hidden> Date: 2004-06-06 16:30:30
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Hi!
Robin Bowes wrote:
On Fri, June 4, 2004 7:29, Neil Brown said:
quoted
- 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@xss.co.at
*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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From: Joe Pruett <hidden> Date: 2004-06-07 15:54:49
You don't need LVM and thus you have one less layer
with potential failures and errors.
using lvm for just partitioning would be silly. but lvm gives you much
more than that. the ability to span partitions over multiple raid arrays.
and the main reason i use it is to be able to grow/shrink storage if
something changes in the future.
From: Mario 'BitKoenig' Holbe <hidden> Date: 2004-06-08 14:11:43
Joe Pruett [off-list ref] wrote:
using lvm for just partitioning would be silly. but lvm gives you much
You got the point :)
more than that. the ability to span partitions over multiple raid arrays.
And if you don't need or want all that, it would
be silly to use LVM - as you mentioned above :)
That's why it makes sense to be able to partition
RAIDs without the need of LVM.
regards,
Mario
--
I thought the only thing the internet was good for was porn. -- Futurama
From: Clemens Schwaighofer <hidden> Date: 2004-06-09 07:01:43
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Andreas Haumer wrote:
| 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?
Well I'd say to leave out one area of problems. LVM might get buggy or
cause troubles. And if you can create partitions in a SW raid you can
avoid that.
eg on a firewall I want only real necessary software and LVM is
definitly not one of them ...
- --
Clemens Schwaighofer - IT Engineer & System Administration
==========================================================
TEQUILA\Japan, 6-17-2 Ginza Chuo-ku, Tokyo 104-8167, JAPAN
Tel: +81-(0)3-3545-7703 Fax: +81-(0)3-3545-7343
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