Hello Neil,
On 07/10/2017 01:03 PM, Veljko wrote:
On 07/10/2017 12:37 AM, NeilBrown wrote:
I wasn't clear to me that I needed to chime in.. and the complete lack
of details (not even an "mdadm --examine" output), meant I could only
answer in vague generalizations.
However, seeing you asked.
If you really want to have a 'linear' of 2 RAID10s, then
0/ unmount the xfs filesystem
1/ backup the last few megabytes of the device
dd if=/dev/mdXX of=/safe/place/backup bs=1M skip=$BIGNUM
2/ create a linear array of the two RAID10s, ensuring the
metadata is v1.0, and the dataoffset is zero (should be default with
1.0)
mdadm -C /dev/mdZZ -l linear -n 2 -e 1.0 --data-offset=0 /dev/mdXX
/dev/mdYY
3/ restore the saved data
dd of=/dev/mdZZ if=/safe/place/backup bs=1M seek=$BIGNUM
4/ grow the xfs filesystem
5/ be happy.
I cannot comment on the values of "few" and "$BUGNUM" without seeing
specifics.
NeilBrown
Thanks for your response, Neil!
md0 is boot (raid1), md1 is root (raid10) and md2 is data (raid10) that
I need to expand. Here are details:
# mdadm --detail /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Mon Sep 10 14:45:11 2012
Raid Level : raid1
Array Size : 488128 (476.77 MiB 499.84 MB)
Used Dev Size : 488128 (476.77 MiB 499.84 MB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Mon Jul 3 11:57:24 2017
State : clean
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Name : backup1:0 (local to host backup1)
UUID : e5a17766:b4df544d:c2770d6e:214113ec
Events : 302
Number Major Minor RaidDevice State
2 8 18 0 active sync /dev/sdb2
3 8 34 1 active sync /dev/sdc2
# mdadm --detail /dev/md1
/dev/md1:
Version : 1.2
Creation Time : Fri Sep 14 12:39:00 2012
Raid Level : raid10
Array Size : 97590272 (93.07 GiB 99.93 GB)
Used Dev Size : 48795136 (46.53 GiB 49.97 GB)
Raid Devices : 4
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Mon Jul 10 12:30:46 2017
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Layout : near=2
Chunk Size : 512K
Name : backup1:1 (local to host backup1)
UUID : 91560d5a:245bbc56:cc08b0ce:9c78fea1
Events : 1003350
Number Major Minor RaidDevice State
4 8 19 0 active sync set-A /dev/sdb3
6 8 35 1 active sync set-B /dev/sdc3
7 8 50 2 active sync set-A /dev/sdd2
5 8 2 3 active sync set-B /dev/sda2
# mdadm --detail /dev/md2
/dev/md2:
Version : 1.2
Creation Time : Fri Sep 14 12:40:13 2012
Raid Level : raid10
Array Size : 5761631232 (5494.72 GiB 5899.91 GB)
Used Dev Size : 2880815616 (2747.36 GiB 2949.96 GB)
Raid Devices : 4
Total Devices : 4
Persistence : Superblock is persistent
Update Time : Mon Jul 10 12:32:51 2017
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0
Layout : near=2
Chunk Size : 512K
Name : backup1:2 (local to host backup1)
UUID : f6eeaa57:a55f36ff:6980a62a:d4781e44
Events : 2689040
Number Major Minor RaidDevice State
4 8 20 0 active sync set-A /dev/sdb4
6 8 36 1 active sync set-B /dev/sdc4
7 8 51 2 active sync set-A /dev/sdd3
5 8 3 3 active sync set-B /dev/sda3
And here is examine output for md2 partitions:
# mdadm --examine /dev/sda3
/dev/sda3:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : f6eeaa57:a55f36ff:6980a62a:d4781e44
Name : backup1:2 (local to host backup1)
Creation Time : Fri Sep 14 12:40:13 2012
Raid Level : raid10
Raid Devices : 4
Avail Dev Size : 5762609152 (2747.83 GiB 2950.46 GB)
Array Size : 5761631232 (5494.72 GiB 5899.91 GB)
Used Dev Size : 5761631232 (2747.36 GiB 2949.96 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262064 sectors, after=977920 sectors
State : clean
Device UUID : 92beeec2:7ff92b1d:473a9641:2a078b16
Update Time : Mon Jul 10 12:35:53 2017
Checksum : d1abfc30 - correct
Events : 2689040
Layout : near=2
Chunk Size : 512K
Device Role : Active device 3
Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)
# mdadm --examine /dev/sdb4
/dev/sdb4:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : f6eeaa57:a55f36ff:6980a62a:d4781e44
Name : backup1:2 (local to host backup1)
Creation Time : Fri Sep 14 12:40:13 2012
Raid Level : raid10
Raid Devices : 4
Avail Dev Size : 5761632256 (2747.36 GiB 2949.96 GB)
Array Size : 5761631232 (5494.72 GiB 5899.91 GB)
Used Dev Size : 5761631232 (2747.36 GiB 2949.96 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262064 sectors, after=1024 sectors
State : clean
Device UUID : 01e1cb21:01a011a9:85761911:9b4d437a
Update Time : Mon Jul 10 12:37:00 2017
Checksum : ef9b6012 - correct
Events : 2689040
Layout : near=2
Chunk Size : 512K
Device Role : Active device 0
Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)
# mdadm --examine /dev/sdc4
/dev/sdc4:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : f6eeaa57:a55f36ff:6980a62a:d4781e44
Name : backup1:2 (local to host backup1)
Creation Time : Fri Sep 14 12:40:13 2012
Raid Level : raid10
Raid Devices : 4
Avail Dev Size : 5761632256 (2747.36 GiB 2949.96 GB)
Array Size : 5761631232 (5494.72 GiB 5899.91 GB)
Used Dev Size : 5761631232 (2747.36 GiB 2949.96 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262064 sectors, after=1024 sectors
State : clean
Device UUID : 1a2c966f:a78ffaf3:83cf37d4:135087b7
Update Time : Mon Jul 10 12:37:53 2017
Checksum : 88b0f680 - correct
Events : 2689040
Layout : near=2
Chunk Size : 512K
Device Role : Active device 1
Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)
# mdadm --examine /dev/sdd3
/dev/sdd3:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : f6eeaa57:a55f36ff:6980a62a:d4781e44
Name : backup1:2 (local to host backup1)
Creation Time : Fri Sep 14 12:40:13 2012
Raid Level : raid10
Raid Devices : 4
Avail Dev Size : 5762609152 (2747.83 GiB 2950.46 GB)
Array Size : 5761631232 (5494.72 GiB 5899.91 GB)
Used Dev Size : 5761631232 (2747.36 GiB 2949.96 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262064 sectors, after=977920 sectors
State : clean
Device UUID : 52f92e76:15228eee:a20c1ee5:8d4a17d2
Update Time : Mon Jul 10 12:38:24 2017
Checksum : b56275df - correct
Events : 2689040
Layout : near=2
Chunk Size : 512K
Device Role : Active device 2
Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)
Do you know what would be the "few" and "$BIGNUM" values from the output
above?
Since I need to expand md2 device, I guess `that I need to subtract
"few" number of megabytes as ($few x 1024 x 1024) in bytes from array
size of md2 (in my case 5761631232). Is this correct? $BIGNUM is the
size of md2 array? How to know how many megabytes needs to be backed up?
Data offset is not zero on md2 partitions. Is that a dealbreaker?
Would it be than better to reshape the current RAID10 to increase the
number of devices used from 4 to 8 (as advised by Roman)?
Regards,
Veljko
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