[lug] Identical UUID for MD devices?
stimits at comcast.net
stimits at comcast.net
Thu Feb 8 12:46:51 MST 2018
When I had to replace a windows disk and didn't want to mess with reactivating everything (it was the same computer, just the disk being replaced) I used Linux to copy from that disk to another of the same exact model. I used dd. This left the UUID as an exact clone, whereas running something like mkfs.ntfs would cause a change. The UUID is just part of the file system like any other data. If the mirror operating was done by raw byte copy I'd expect UUIDs to be a clone.
----- Original Message -----From: Rob Nagler <nagler at bivio.biz>To: Boulder (Colorado) Linux Users Group -- General Mailing List <lug at lug.boulder.co.us>Sent: Thu, 08 Feb 2018 16:25:17 -0000 (UTC)Subject: [lug] Identical UUID for MD devices?
I created two RAID1 devices with mdadm, but the UUIDs are identical (see below). I actually created and destroyed an array with all four disks, wiped the signatures, and then recreated the arrays as separate mirrored disks. I'm going to recreate the arrays, but I was wondering if someone had seen this before. Thanks, Rob
# lsblk -o +UUID
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT UUID
sda 8:0 0 7.3T 0 disk a0793173-d347-8d42-4b5b-8ae915570d5e
└─md3 9:3 0 7.3T 0 raid1 38bc1e03-f953-4104-84b4-fbf78b5895d4
sdb 8:16 0 7.3T 0 disk a0793173-d347-8d42-4b5b-8ae915570d5e
└─md3 9:3 0 7.3T 0 raid1 38bc1e03-f953-4104-84b4-fbf78b5895d4
sdc 8:32 0 7.3T 0 disk f6f1266c-1f97-4ff8-f142-6979a84ba08a
└─md4 9:4 0 7.3T 0 raid1 38bc1e03-f953-4104-84b4-fbf78b5895d4
sdd 8:48 0 7.3T 0 disk f6f1266c-1f97-4ff8-f142-6979a84ba08a
└─md4 9:4 0 7.3T 0 raid1 38bc1e03-f953-4104-84b4-fbf78b5895d4
sde 8:64 0 238.5G 0 disk
├─sde1 8:65 0 1G 0 part 97e01b29-f07f-5064-040c-4a2620141498
│ └─md0 9:0 0 1023M 0 raid1 /boot b35251df-1483-4b5d-8c5a-d2d4cd72091d
└─sde2 8:66 0 237.5G 0 part c73e71b6-e620-2f74-3c77-d0f423ee9247
└─md2 9:2 0 237.4G 0 raid1 e1f57619-ef51-48f4-bab6-fd080522cd68
└─luks-e1f57619-ef51-48f4-bab6-fd080522cd68 253:0 0 237.4G 0 crypt aqyS9B-z8kQ-GYeA-OaQF-s1Ux-DnAy-3ucPpN
└─centos-root 253:1 0 5G 0 lvm / 518ac627-bc81-4ea7-9df2-b84b43c2e90f
sdf 8:80 0 238.5G 0 disk
├─sdf1 8:81 0 1G 0 part 97e01b29-f07f-5064-040c-4a2620141498
│ └─md0 9:0 0 1023M 0 raid1 /boot b35251df-1483-4b5d-8c5a-d2d4cd72091d
└─sdf2 8:82 0 237.5G 0 part c73e71b6-e620-2f74-3c77-d0f423ee9247
└─md2 9:2 0 237.4G 0 raid1 e1f57619-ef51-48f4-bab6-fd080522cd68
└─luks-e1f57619-ef51-48f4-bab6-fd080522cd68 253:0 0 237.4G 0 crypt aqyS9B-z8kQ-GYeA-OaQF-s1Ux-DnAy-3ucPpN
└─centos-root 253:1 0 5G 0 lvm / 518ac627-bc81-4ea7-9df2-b84b43c2e90f
# ls -1 /dev/disk/by-uuid/
38bc1e03-f953-4104-84b4-fbf78b5895d4
518ac627-bc81-4ea7-9df2-b84b43c2e90f
b35251df-1483-4b5d-8c5a-d2d4cd72091d
e1f57619-ef51-48f4-bab6-fd080522cd68
# mdadm --detail /dev/md/3
/dev/md/3:
Version : 1.2
Creation Time : Thu Feb 8 15:29:12 2018
Raid Level : raid1
Array Size : 7813895488 (7451.91 GiB 8001.43 GB)
Used Dev Size : 7813895488 (7451.91 GiB 8001.43 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : Thu Feb 8 16:21:11 2018
State : clean, resyncing
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Consistency Policy : bitmap
Resync Status : 5% complete
Name : localhost.localdomain:3 (local to host localhost.localdomain)
UUID : a0793173:d3478d42:4b5b8ae9:15570d5e
Events : 491
Number Major Minor RaidDevice State
0 8 0 0 active sync /dev/sda
1 8 16 1 active sync /dev/sdb
# mdadm --detail /dev/md/4
/dev/md/4:
Version : 1.2
Creation Time : Thu Feb 8 15:29:28 2018
Raid Level : raid1
Array Size : 7813895488 (7451.91 GiB 8001.43 GB)
Used Dev Size : 7813895488 (7451.91 GiB 8001.43 GB)
Raid Devices : 2
Total Devices : 2
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : Thu Feb 8 16:21:31 2018
State : clean, resyncing
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Consistency Policy : bitmap
Resync Status : 5% complete
Name : localhost.localdomain:4 (local to host localhost.localdomain)
UUID : f6f1266c:1f974ff8:f1426979:a84ba08a
Events : 491
Number Major Minor RaidDevice State
0 8 32 0 active sync /dev/sdc
1 8 48 1 active sync /dev/sdd
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.lug.boulder.co.us/pipermail/lug/attachments/20180208/c7f426f4/attachment.html>
More information about the LUG
mailing list