Move rpool (raidz1) to smaller disks

[Denny Fuchs]

Hello,

we have to migrate a rpool on a raidz, to smaller disks and asking for the best way.

At the moment we use 2 x Crucial M550 1TB (953.9GB) disks and want to switch to 2 x Samsung 960 1TB (894.3GB). The Samsungs are slightly smaller, so we can't just replace them. The next problem is, that the node has only two HDD slots, so I can't just add the new disks ...

So, the only way is USB or SSH .... If I use USB ... I think, I can't name the pool "rpool", because the name already exists ...

So, what is the best way to "clone" the complete rpool, so that I can switch the disks and add the second Samsung and have a working raidz again ?

cu denny

 

[fireon]

First i 've never done this. But it should work like this:

sgdisk -Z -o /dev/disk/by-id/XXX
sgdisk -Z /dev/disk/by-id/XXX
sgdisk -a1 -n1:34:2047 -t1:EF02 -n9:-8M:0 -t9:BF07 -n2:2048:0 -t2:BF01 -c 2:zfs /dev/disk/by-id/XXX
zfs snapshot rpool/ROOT/pve-1@migration
zfs send -v rpool/ROOT/pve-1@migration | zfs receive  newpool/datasetname

After that you must write grub:

update-grub2
grub-intall /dev/disk/by-id/XXX

And then you must say to the system it should boot from... for example: "rpoolnew". Never done this before. So search a little bit on oracle documentation.

This is on of our reasons why we install only the rpool on two extra SSD's. Everything is easier to do.

 

[Denny Fuchs]

hi,

here is, what I have done:
Requirements:

• A USB stick
• A PC/Laptop that is able to boot the Linux in the stick
• The ISO Image: http://list.zfsonlinux.org/zfs-iso/sysresccd-5.0.2_zfs_0.7.0.iso
• New disk / SSD directly connected (SATA) or via USB (here as /dev/sdb)
  
• Network cable ;-)
• A bit time

1. Create USB Stick with ZFS on it: https://wiki.gentoo.org/wiki/User:Fearedbliss/Installing_Gentoo_Linux_On_ZFS
   I used this Image: http://list.zfsonlinux.org/zfs-iso/sysresccd-5.0.2_zfs_0.7.0.iso
2. Connect the new SSD/Disk on the Laptop/PC
3. sgdisk -Z -o /dev/disk/sdb
4. sgdisk -Z /dev/disk/by-id/sdb
5. Create the partitions GPT:
   sgdisk -a1 -n1:34:2047 -t1:EF02 -n9:-8M:0 -t9:BF07 -n2:2048:0 -t2:BF01 -c 2:zfs /dev/sdb
6. Create the new "rpool" zpool, but with deactivated features, if needed (!!). Compare with zpool get all, otherwise you can't import the pool, because of new features, that ZFS version from PVE doesn't have.
   zpool create -d -o ashift=12 -o feature@sha512=disabled -o feature@skein=disabled -o feature@userobj_accounting=disabled rpool

On the target host, do:

1. Shutdown all VMs (!)
   
2. Remove the swapfs (!)
   swapoff
   zfs destroy -f rpool/swap
   
3. Create the snapshot for the whole rpool
   zfs snapshot -r rpool@migration
4. Connect both hosts via network
5. copy / create SSH key from the host to the laptop/pc and test or use netcat version
   
6. Copy now the whole rpool snaphot via SSH:
   SSH version: zfs send -Rv rpool@migration | ssh <laptop/pc> zfs receive -vF rpool
   Netcat version sender: zfs send -Rv rpool@migration | nc -w 20 <laptop/pc> 8023
   Netcat version receiver: nc -w 120 -l -p 8023 | zfs receive -vF rpool

After the copyjob is done, reinstall Grub on the new disk (Laptop/PC):

1. zpool export rpool
2. mkdir /bla
3. zpool import -a -N -R /bla
4. zfs mount rpool/ROOT/pve-1
5. mount --bind /dev /bla/dev
6. mount --bind /proc /bla/proc
7. mount --bind /sys /bla/sys
8. chroot /bla /bin/bash
9. mv /boot/grub/grub.cfg /boot/grub/grub.cfg.migration
10. update-grub
11. grub-install /dev/sdb
12. exit
13. Create swapfs
    zfs create -o sync=always -o primarycache=none -b 4k -V 8G -o logbias=throughput rpool/swap
    mkswap -f /dev/zvol/rpool/swap

Now you can poweroff both hosts and replace/swap the disks. If all is done, the snapshot could be deleted on the new disk with zfs destroy -f rpool@migration and all other (zfs list -t snapshots)

The only problem I had, was the the ZFS version on the USB stick created a Zpool with features, the the PVE ZFS version doesn't have, so that it wasn't possible to import the Zpool with the PVE kernel. So I had to recreate and copy the whole system again.

@fireon Thanks for the sgdisk commands

Update:

In german, with a bit more text: https://www.pug.org/mediawiki/index.php/Zpool_migrieren

 

[fireon]

@Denny Fuchs Thanks for share your experience!

 

[babas24]

nc