upgrade of an iSCSI zpool mirror

[Julien Cigar]

Hello,

We have a "low-cost" active/passive HA ZFS based filer (with 
NFS4/SMB/... on top) which consist of two tiny HP Proliant DL20 
with 2 x 2 To disks in each. On the PASSIVE node two slices are exported
through iSCSI, and on the ACTIVE node a zpool mirror (named "data") has 
been created over two local slices and the two iSCSI slices. 
Failover from ACTIVE to PASSIVE is made through CARP and a failover 
script, while failover from OLD ACTIVE (NOW PASSIVE) to NEW ACTIVE (now 
ACTIVE) is done manually (the failover script explicitely change the 
advskew to avoid any possible side effects)

It works well, but those are still running FreeBSD 10.3 and I'd like to
upgrade to 11.x. During the upgrade process the pool should be read-only
available. I planned to do something like:

with F1 being the (current) ACTIVE node and F2 being the (current) 
PASSIVE node:

- stop NFS/... services on F1
- zpool export data on F1
- switch CARP roles
- F1 is now the PASSIVE node and F2 is now the ACTIVE node
- on F2: zpool import -o readonly=on data
- start NFS/... services on F2
- then start to upgrade of F1

once the upgrade of F1 is finished:
- stop NFS/... services on F2
- zpool export data on F2
- switch CARP roles
- F2 is now the PASSIVE node and F1 is now the ACTIVE node
- on F1: zpool import data
- on F1: zpool detach data <the two iSCSI disks from F2>
- start NFS/... services on F1

then start the upgrade of F2, once finished re-attach the two iSCSI
disks from F2 to the data pool on F1, and run a zpool scrub

Has anyone ever done something similar and/or does it sound good to you?

Thanks,
Julien

-- 
Julien Cigar
Belgian Biodiversity Platform (http://www.biodiversity.be)
PGP fingerprint: EEF9 F697 4B68 D275 7B11  6A25 B2BB 3710 A204 23C0
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