Configure RAID before Deploy OS¶
Overview¶
This section describes how to use xCAT to deploy diskful nodes with RAID1 setup, and the procedure for RAID1 maintainence activities such as replacing a failed disk.
All the examples in this section are based on three configuration scenarios:
- RHEL6 on a system p machine with two SCSI disks sda and sdb
- RHEL6 on a system p machine with two SAS disks and multipath configuration.
- SLES 11 SP1 on a system p machine with two SCSI disks sda and sdb
If you are not using the configuration scenarios listed above, you may need to modify some of the steps in this documentation to make it work in your environment.
Deploy Diskful Nodes with RAID1 Setup on RedHat¶
xCAT provides two sample kickstart template files with the RAID1 settings, /opt/xcat/share/xcat/install/rh/service.raid1.rhel6.ppc64.tmpl is for the configuration scenario 1 listed above and /opt/xcat/share/xcat/install/rh/service.raid1.multipath.rhel6.ppc64.tmpl is for the configuration scenario 2 listed above. You can customize the template file and put it under /install/custom/install/<platform>/ if the default one does not match your requirements.
Here is the RAID1 partitioning section in service.raid1.rhel6.ppc64.tmpl:
#Full RAID 1 Sample
part None --fstype "PPC PReP Boot" --size 8 --ondisk sda --asprimary
part None --fstype "PPC PReP Boot" --size 8 --ondisk sdb --asprimary
part raid.01 --size 200 --fstype ext4 --ondisk sda
part raid.02 --size 200 --fstype ext4 --ondisk sdb
raid /boot --level 1 --device md0 raid.01 raid.02
part raid.11 --size 1024 --ondisk sda
part raid.12 --size 1024 --ondisk sdb
raid swap --level 1 --device md1 raid.11 raid.12
part raid.21 --size 1 --fstype ext4 --grow --ondisk sda
part raid.22 --size 1 --fstype ext4 --grow --ondisk sdb
raid / --level 1 --device md2 raid.21 raid.22
Here is the RAID1 partitioning section in service.raid1.multipath.rhel6.ppc64.tmpl:
#Full RAID 1 Sample
part None --fstype "PPC PReP Boot" --size 8 --ondisk mpatha --asprimary
part None --fstype "PPC PReP Boot" --size 8 --ondisk mpathb --asprimary
part raid.01 --size 200 --fstype ext4 --ondisk mpatha
part raid.02 --size 200 --fstype ext4 --ondisk mpathb
raid /boot --level 1 --device md0 raid.01 raid.02
part raid.11 --size 1024 --ondisk mpatha
part raid.12 --size 1024 --ondisk mpathb
raid swap --level 1 --device md1 raid.11 raid.12
part raid.21 --size 1 --fstype ext4 --grow --ondisk mpatha
part raid.22 --size 1 --fstype ext4 --grow --ondisk mpathb
raid / --level 1 --device md2 raid.21 raid.22
The samples above created one PReP partition, one 200MB /boot partition and one / partition on sda/sdb and mpatha/mpathb. If you want to use different partitioning scheme in your cluster, modify this RAID1 section in the kickstart template file accordingly.
After the diskful nodes are up and running, you can check the RAID1 settings with the following commands:
Mount command shows the /dev/mdx devices are mounted to various file systems, the /dev/mdx indicates that the RAID is being used on this node.
# mount
/dev/md2 on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw)
/dev/md0 on /boot type ext4 (rw)
none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
The file /proc/mdstat includes the RAID devices status on the system, here is an example of /proc/mdstat in the non-multipath environment:
# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 sda5[0] sdb5[1]
19706812 blocks super 1.1 [2/2] [UU]
bitmap: 1/1 pages [64KB], 65536KB chunk
md1 : active raid1 sda2[0] sdb2[1]
1048568 blocks super 1.1 [2/2] [UU]
md0 : active raid1 sda3[0] sdb3[1]
204788 blocks super 1.0 [2/2] [UU]
unused devices: <none>
On the system with multipath configuration, the /proc/mdstat looks like:
# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 dm-11[0] dm-6[1]
291703676 blocks super 1.1 [2/2] [UU]
bitmap: 1/1 pages [64KB], 65536KB chunk
md1 : active raid1 dm-8[0] dm-3[1]
1048568 blocks super 1.1 [2/2] [UU]
md0 : active raid1 dm-9[0] dm-4[1]
204788 blocks super 1.0 [2/2] [UU]
unused devices: <none>
The command mdadm can query the detailed configuration for the RAID partitions:
mdadm --detail /dev/md2
Deploy Diskful Nodes with RAID1 Setup on SLES¶
xCAT provides one sample autoyast template files with the RAID1 settings /opt/xcat/share/xcat/install/sles/service.raid1.sles11.tmpl. You can customize the template file and put it under /install/custom/install/<platform>/ if the default one does not match your requirements.
Here is the RAID1 partitioning section in service.raid1.sles11.tmpl:
<partitioning config:type="list">
<drive>
<device>/dev/sda</device>
<partitions config:type="list">
<partition>
<format config:type="boolean">false</format>
<partition_id config:type="integer">65</partition_id>
<partition_nr config:type="integer">1</partition_nr>
<partition_type>primary</partition_type>
<size>24M</size>
</partition>
<partition>
<format config:type="boolean">false</format>
<partition_id config:type="integer">253</partition_id>
<partition_nr config:type="integer">2</partition_nr>
<raid_name>/dev/md0</raid_name>
<raid_type>raid</raid_type>
<size>2G</size>
</partition>
<partition>
<format config:type="boolean">false</format>
<partition_id config:type="integer">253</partition_id>
<partition_nr config:type="integer">3</partition_nr>
<raid_name>/dev/md1</raid_name>
<raid_type>raid</raid_type>
<size>max</size>
</partition>
</partitions>
<use>all</use>
</drive>
<drive>
<device>/dev/sdb</device>
<partitions config:type="list">
<partition>
<format config:type="boolean">false</format>
<partition_id config:type="integer">131</partition_id>
<partition_nr config:type="integer">1</partition_nr>
<partition_type>primary</partition_type>
<size>24M</size>
</partition>
<partition>
<format config:type="boolean">false</format>
<partition_id config:type="integer">253</partition_id>
<partition_nr config:type="integer">2</partition_nr>
<raid_name>/dev/md0</raid_name>
<raid_type>raid</raid_type>
<size>2G</size>
</partition>
<partition>
<format config:type="boolean">false</format>
<partition_id config:type="integer">253</partition_id>
<partition_nr config:type="integer">3</partition_nr>
<raid_name>/dev/md1</raid_name>
<raid_type>raid</raid_type>
<size>max</size>
</partition>
</partitions>
<use>all</use>
</drive>
<drive>
<device>/dev/md</device>
<partitions config:type="list">
<partition>
<filesystem config:type="symbol">reiser</filesystem>
<format config:type="boolean">true</format>
<mount>swap</mount>
<partition_id config:type="integer">131</partition_id>
<partition_nr config:type="integer">0</partition_nr>
<raid_options>
<chunk_size>4</chunk_size>
<parity_algorithm>left-asymmetric</parity_algorithm>
<raid_type>raid1</raid_type>
</raid_options>
</partition>
<partition>
<filesystem config:type="symbol">reiser</filesystem>
<format config:type="boolean">true</format>
<mount>/</mount>
<partition_id config:type="integer">131</partition_id>
<partition_nr config:type="integer">1</partition_nr>
<raid_options>
<chunk_size>4</chunk_size>
<parity_algorithm>left-asymmetric</parity_algorithm>
<raid_type>raid1</raid_type>
</raid_options>
</partition>
</partitions>
<use>all</use>
</drive>
</partitioning>
The samples above created one 24MB PReP partition on each disk, one 2GB mirrored swap partition and one mirrored / partition uses all the disk space. If you want to use different partitioning scheme in your cluster, modify this RAID1 section in the autoyast template file accordingly.
Since the PReP partition can not be mirrored between the two disks, some additional postinstall commands should be run to make the second disk bootable, here the the commands needed to make the second disk bootable:
# Set the second disk to be bootable for RAID1 setup
parted -s /dev/sdb mkfs 1 fat16
parted /dev/sdb set 1 type 6
parted /dev/sdb set 1 boot on
dd if=/dev/sda1 of=/dev/sdb1
bootlist -m normal sda sdb
The procedure listed above has been added to the file /opt/xcat/share/xcat/install/scripts/post.sles11.raid1 to make it be automated. The autoyast template file service.raid1.sles11.tmpl will include the content of post.sles11.raid1, so no manual steps are needed here.
After the diskful nodes are up and running, you can check the RAID1 settings with the following commands:
Mount command shows the /dev/mdx devices are mounted to various file systems, the /dev/mdx indicates that the RAID is being used on this node.
server:~ # mount
/dev/md1 on / type reiserfs (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
debugfs on /sys/kernel/debug type debugfs (rw)
devtmpfs on /dev type devtmpfs (rw,mode=0755)
tmpfs on /dev/shm type tmpfs (rw,mode=1777)
devpts on /dev/pts type devpts (rw,mode=0620,gid=5)
The file /proc/mdstat includes the RAID devices status on the system, here is an example of /proc/mdstat:
server:~ # cat /proc/mdstat
Personalities : [raid1] [raid0] [raid10] [raid6] [raid5] [raid4]
md0 : active (auto-read-only) raid1 sda2[0] sdb2[1]
2104500 blocks super 1.0 [2/2] [UU]
bitmap: 0/1 pages [0KB], 128KB chunk
md1 : active raid1 sda3[0] sdb3[1]
18828108 blocks super 1.0 [2/2] [UU]
bitmap: 0/9 pages [0KB], 64KB chunk
unused devices: <none>
The command mdadm can query the detailed configuration for the RAID partitions:
mdadm --detail /dev/md1
Disk Replacement Procedure¶
If any one disk fails in the RAID1 arrary, do not panic. Follow the procedure listed below to replace the failed disk and you will be fine.
Faulty disks should appear marked with an (F) if you look at /proc/mdstat:
# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 dm-11[0](F) dm-6[1]
291703676 blocks super 1.1 [2/1] [_U]
bitmap: 1/1 pages [64KB], 65536KB chunk
md1 : active raid1 dm-8[0](F) dm-3[1]
1048568 blocks super 1.1 [2/1] [_U]
md0 : active raid1 dm-9[0](F) dm-4[1]
204788 blocks super 1.0 [2/1] [_U]
unused devices: <none>
We can see that the first disk is broken because all the RAID partitions on this disk are marked as (F).
Remove the failed disk from RAID arrary¶
mdadm is the command that can be used to query and manage the RAID arrays on Linux. To remove the failed disk from RAID array, use the command:
mdadm --manage /dev/mdx --remove /dev/xxx
Where the /dev/mdx are the RAID partitions listed in /proc/mdstat file, such as md0, md1 and md2; the /dev/xxx are the backend devices like dm-11, dm-8 and dm-9 in the multipath configuration and sda5, sda3 and sda2 in the non-multipath configuration.
Here is the example of removing failed disk from the RAID1 array in the non-multipath configuration:
mdadm --manage /dev/md0 --remove /dev/sda3
mdadm --manage /dev/md1 --remove /dev/sda2
mdadm --manage /dev/md2 --remove /dev/sda5
Here is the example of removing failed disk from the RAID1 array in the multipath configuration:
mdadm --manage /dev/md0 --remove /dev/dm-9
mdadm --manage /dev/md1 --remove /dev/dm-8
mdadm --manage /dev/md2 --remove /dev/dm-11
After the failed disk is removed from the RAID1 array, the partitions on the failed disk will be removed from /proc/mdstat and the “mdadm –detail” output also.
# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 dm-6[1]
291703676 blocks super 1.1 [2/1] [_U]
bitmap: 1/1 pages [64KB], 65536KB chunk
md1 : active raid1 dm-3[1]
1048568 blocks super 1.1 [2/1] [_U]
md0 : active raid1 dm-4[1]
204788 blocks super 1.0 [2/1] [_U]
unused devices: <none>
# mdadm --detail /dev/md0
/dev/md0:
Version : 1.0
Creation Time : Tue Jul 19 02:39:03 2011
Raid Level : raid1
Array Size : 204788 (200.02 MiB 209.70 MB)
Used Dev Size : 204788 (200.02 MiB 209.70 MB)
Raid Devices : 2
Total Devices : 1
Persistence : Superblock is persistent
Update Time : Wed Jul 20 02:00:04 2011
State : clean, degraded
Active Devices : 1
Working Devices : 1
Failed Devices : 0
Spare Devices : 0
Name : c250f17c01ap01:0 (local to host c250f17c01ap01)
UUID : eba4d8ad:8f08f231:3c60e20f:1f929144
Events : 26
Number Major Minor RaidDevice State
0 0 0 0 removed
1 253 4 1 active sync /dev/dm-4
Replace the disk¶
Depends on the hot swap capability, you may simply unplug the disk and replace with a new one if the hot swap is supported; otherwise, you will need to power off the machine and replace the disk and the power on the machine. Create partitions on the new disk
The first thing we must do now is to create the exact same partitioning as on the new disk. We can do this with one simple command:
sfdisk -d /dev/<good_disk> | sfdisk /dev/<new_disk>
For the non-mulipath configuration, here is an example:
sfdisk -d /dev/sdb | sfdisk /dev/sda
For the multipath configuration, here is an example:
sfdisk -d /dev/dm-1 | sfdisk /dev/dm-0
If you got error message “sfdisk: I don’t like these partitions - nothing changed.”, you can add “–force” option to the sfdisk command:
sfdisk -d /dev/sdb | sfdisk /dev/sda --force
You can run:
fdisk -l
To check if both hard drives have the same partitioning now.
Add the new disk into the RAID1 array¶
After the partitions are created on the new disk, you can use command:
mdadm --manage /dev/mdx --add /dev/xxx
To add the new disk to the RAID1 array. Where the /dev/mdx are the RAID partitions like md0, md1 and md2; the /dev/xxx are the backend devices like dm-11, dm-8 and dm-9 in the multipath configuration and sda5, sda3 and sda2 in the non-multipath configuration.
Here is an example for the non-multipath configuration:
mdadm --manage /dev/md0 --add /dev/sda3
mdadm --manage /dev/md1 --add /dev/sda2
mdadm --manage /dev/md2 --add /dev/sda5
Here is an example for the multipath configuration:
mdadm --manage /dev/md0 --add /dev/dm-9
mdadm --manage /dev/md1 --add /dev/dm-8
mdadm --manage /dev/md2 --add /dev/dm-11
All done! You can have a cup of coffee to watch the fully automatic reconstruction running...
While the RAID1 array is reconstructing, you will see some progress information in /proc/mdstat:
# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 dm-11[0] dm-6[1]
291703676 blocks super 1.1 [2/1] [_U]
[>....................] recovery = 0.7% (2103744/291703676) finish=86.2min speed=55960K/sec
bitmap: 1/1 pages [64KB], 65536KB chunk
md1 : active raid1 dm-8[0] dm-3[1]
1048568 blocks super 1.1 [2/1] [_U]
[=============>.......] recovery = 65.1% (683904/1048568) finish=0.1min speed=48850K/sec
md0 : active raid1 dm-9[0] dm-4[1]
204788 blocks super 1.0 [2/1] [_U]
[===================>.] recovery = 96.5% (198016/204788) finish=0.0min speed=14144K/sec
unused devices: <none>
After the reconstruction is done, the /proc/mdstat becomes like:
# cat /proc/mdstat
Personalities : [raid1]
md2 : active raid1 dm-11[0] dm-6[1]
291703676 blocks super 1.1 [2/2] [UU]
bitmap: 1/1 pages [64KB], 65536KB chunk
md1 : active raid1 dm-8[0] dm-3[1]
1048568 blocks super 1.1 [2/2] [UU]
md0 : active raid1 dm-9[0] dm-4[1]
204788 blocks super 1.0 [2/2] [UU]
unused devices: <none>
Make the new disk bootable¶
If the new disk does not have a PReP partition or the PReP partition has some problem, it will not be bootable, here is an example on how to make the new disk bootable, you may need to substitute the device name with your own values.
[RHEL]:
mkofboot .b /dev/sda bootlist -m normal sda sdb
[SLES]:
parted -s /dev/sda mkfs 1 fat16 parted /dev/sda set 1 type 6 parted /dev/sda set 1 boot on dd if=/dev/sdb1 of=/dev/sda1 bootlist -m normal sda sdb