Hi,
I have a problem that might be a bit unusual.
Using an Intel 82801, we create in the BIOS a RAID 5 with 3 disks,
spanning the whole disks. After that we boot Linux via the network
into an initial ramdisk (buildroot) to assemble and format the array.
Currently I use kernel 3.7.8, mdadm 3.2.6 and the following commands
to start the array:
mdadm --assemble --scan -e imsm
mdadm --incremental -e imsm /dev/md/imsm0
After the first command, /proc/mdstat looks like this:
Personalities : [raid6] [raid5] [raid4]
md127 : inactive sdc[2](S) sda[1](S) sdb[0](S)
9459 blocks super external:imsm
After the second command, Linux starts to initialize the array:
Personalities : [raid6] [raid5] [raid4]
md126 : active raid5 sda[2] sdb[1] sdc[0]
1953497088 blocks super external:/md127/0 level 5, 128k chunk, algorithm 0 [3/3] [UUU]
[=>...................] resync = 5.5% (54541952/976748672) finish=86.5min speed=177664K/sec
md127 : inactive sdc[2](S) sda[1](S) sdb[0](S)
9459 blocks super external:imsm
Here is the complete output of mdadm -E /dev/sd*:
/dev/sda:
Magic : Intel Raid ISM Cfg Sig.
Version : 1.2.02
Orig Family : 04e27e25
Family : 04e27e25
Generation : 00000053
Attributes : All supported
UUID : 8d359434:ec976aca:274c42c2:0b38bc28
Checksum : 9b719f6c correct
MPB Sectors : 2
Disks : 3
RAID Devices : 1
Disk00 Serial : Z1D4N2AZ
State : active
Id : 00000000
Usable Size : 1953518862 (931.51 GiB 1000.20 GB)
[Volume1]:
UUID : 7dfa2a6f:6dc8e907:f0559321:3fab80ea
RAID Level : 5 <-- 5
Members : 3 <-- 3
Slots : [UUU] <-- [UUU]
Failed disk : none
This Slot : 0
Array Size : 3906994176 (1863.00 GiB 2000.38 GB)
Per Dev Size : 1953497352 (931.50 GiB 1000.19 GB)
Sector Offset : 0
Num Stripes : 7630848
Chunk Size : 128 KiB <-- 128 KiB
Reserved : 0
Migrate State : initialize
Map State : normal <-- uninitialized
Checkpoint : 141111 (768)
Dirty State : clean
Disk01 Serial : Z1D4MN2C
State : active
Id : 00000001
Usable Size : 1953518862 (931.51 GiB 1000.20 GB)
Disk02 Serial : Z1D4MNG0
State : active
Id : 00000002
Usable Size : 1953518862 (931.51 GiB 1000.20 GB)
/dev/sdb:
Magic : Intel Raid ISM Cfg Sig.
Version : 1.2.02
Orig Family : 04e27e25
Family : 04e27e25
Generation : 00000053
Attributes : All supported
UUID : 8d359434:ec976aca:274c42c2:0b38bc28
Checksum : 9b719f6c correct
MPB Sectors : 2
Disks : 3
RAID Devices : 1
Disk01 Serial : Z1D4MN2C
State : active
Id : 00000001
Usable Size : 1953518862 (931.51 GiB 1000.20 GB)
[Volume1]:
UUID : 7dfa2a6f:6dc8e907:f0559321:3fab80ea
RAID Level : 5 <-- 5
Members : 3 <-- 3
Slots : [UUU] <-- [UUU]
Failed disk : none
This Slot : 1
Array Size : 3906994176 (1863.00 GiB 2000.38 GB)
Per Dev Size : 1953497352 (931.50 GiB 1000.19 GB)
Sector Offset : 0
Num Stripes : 7630848
Chunk Size : 128 KiB <-- 128 KiB
Reserved : 0
Migrate State : initialize
Map State : normal <-- uninitialized
Checkpoint : 141111 (768)
Dirty State : clean
Disk00 Serial : Z1D4N2AZ
State : active
Id : 00000000
Usable Size : 1953518862 (931.51 GiB 1000.20 GB)
Disk02 Serial : Z1D4MNG0
State : active
Id : 00000002
Usable Size : 1953518862 (931.51 GiB 1000.20 GB)
/dev/sdc:
Magic : Intel Raid ISM Cfg Sig.
Version : 1.2.02
Orig Family : 04e27e25
Family : 04e27e25
Generation : 00000053
Attributes : All supported
UUID : 8d359434:ec976aca:274c42c2:0b38bc28
Checksum : 9b719f6c correct
MPB Sectors : 2
Disks : 3
RAID Devices : 1
Disk02 Serial : Z1D4MNG0
State : active
Id : 00000002
Usable Size : 1953518862 (931.51 GiB 1000.20 GB)
[Volume1]:
UUID : 7dfa2a6f:6dc8e907:f0559321:3fab80ea
RAID Level : 5 <-- 5
Members : 3 <-- 3
Slots : [UUU] <-- [UUU]
Failed disk : none
This Slot : 2
Array Size : 3906994176 (1863.00 GiB 2000.38 GB)
Per Dev Size : 1953497352 (931.50 GiB 1000.19 GB)
Sector Offset : 0
Num Stripes : 7630848
Chunk Size : 128 KiB <-- 128 KiB
Reserved : 0
Migrate State : initialize
Map State : normal <-- uninitialized
Checkpoint : 141111 (768)
Dirty State : clean
Disk00 Serial : Z1D4N2AZ
State : active
Id : 00000000
Usable Size : 1953518862 (931.51 GiB 1000.20 GB)
Disk01 Serial : Z1D4MN2C
State : active
Id : 00000001
Usable Size : 1953518862 (931.51 GiB 1000.20 GB)
This would all be perfect if we did use Linux on the machine. However, after dumping
a MS Windows image on it, the machine is shipped to customers, and it is requested
that we don't initialize the array, so that the resync happens when the customer
starts it. Apparently MS Windows has a mode to use the array without initializing it
until requested. (I guess it initializes only the parts of the array that are
actually used, so that it never needs to be initialized explicitly.)
Is this possible with Linux too? Is it reasonable at all? Unfortunately, the option
--assume-clean is not allowed in this mode, and I found no other option that could help.
Thanks
Hans-Joachim
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