makes no sense especially in case of RAID1
* shut down the computer
* replace one disk
* boot
* resync RAID
the old disk is 100% identical and can be seen as a full backup
the whole purpose of RAID is that you can replace disks, frankly it's
desigend to survive a exploding disk at full operations
also you should know what to do when a disk dies - the excatly same
steps with the difference that your old replaced disk currently is a
100% fallback even if you confuse source/target and destroy everything
--------------
in case it's a BIOS setup you can clone the whole partitioning with dd
of the first 512 blocks
the script below is from a setup with 3 RAID1 and doe sthe whole stuff
including install GRUB2 on the new disk - for UEFI you need some steps
more because UUIDs must be unique
* boot
* system
* data
[root@south:~]$ cat /scripts/raid-recovery.sh
#!/usr/bin/bash
# define source and target
GOOD_DISK="/dev/sda"
BAD_DISK="/dev/sdb"
# clone MBR
dd if=$GOOD_DISK of=$BAD_DISK bs=512 count=1
# force OS to read partition tables
partprobe $BAD_DISK
# start RAID recovery
mdadm /dev/md0 --add ${BAD_DISK}1
mdadm /dev/md1 --add ${BAD_DISK}3
mdadm /dev/md2 --add ${BAD_DISK}2
# print RAID status on screen
sleep 5
cat /proc/mdstat
# install bootloader on replacement disk
grub2-install "$BAD_DISK"
Am 03.09.25 um 13:55 schrieb Stefanie Leisestreichler (Febas):
Hi.
I have the system layout shown below.
To avoid data loss, I want to change HDs which have about 46508 hours of
up time.
I thought, instead of degrading, formatting, rebuilding and so on, I could
- shutdown the computer
- take i.e. /dev/sda and do
- dd bs=98304 conv=sync,noerror if=/dev/sda of=/dev/sdX (X standig for
device name of new disk)
Is it save to do it this way, presuming the array is in AA-State?
Thanks,
Steffi
/dev/sda1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 68c0c9ad:82ede879:2110f427:9f31c140
Name : speernix15:0 (local to host speernix15)
Creation Time : Sun Nov 30 19:15:35 2014
Raid Level : raid1
Raid Devices : 2
Avail Dev Size : 1953260976 (931.39 GiB 1000.07 GB)
Array Size : 976629568 (931.39 GiB 1000.07 GB)
Used Dev Size : 1953259136 (931.39 GiB 1000.07 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=261864 sectors, after=1840 sectors
State : active
Device UUID : 5871292c:7fcfbd82:b0a28f1b:df7774f9
Update Time : Thu Aug 28 01:00:03 2025
Bad Block Log : 512 entries available at offset 264 sectors
Checksum : b198f5d1 - correct
Events : 38185
Device Role : Active device 0
Array State : AA ('A' == active, '.' == missing, 'R' == replacing)
/dev/sdb1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : 68c0c9ad:82ede879:2110f427:9f31c140
Name : speernix15:0 (local to host speernix15)
Creation Time : Sun Nov 30 19:15:35 2014
Raid Level : raid1
Raid Devices : 2
Avail Dev Size : 1953260976 (931.39 GiB 1000.07 GB)
Array Size : 976629568 (931.39 GiB 1000.07 GB)
Used Dev Size : 1953259136 (931.39 GiB 1000.07 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=261864 sectors, after=1840 sectors
State : active
Device UUID : 4bbfbe7a:457829a5:dd9d2e3c:15818bca
Update Time : Thu Aug 28 01:00:03 2025
Bad Block Log : 512 entries available at offset 264 sectors
Checksum : 144ff0ef - correct
Events : 38185
