On 12/01/2017 22:57, Stefan Bethke wrote:
Am 12.01.2017 um 23:29 schrieb Stefan Bethke <[email protected]>:
I’ve just created two pools on a freshly partitioned disk, using 11.0 amd64,
and the shift appears to be 9:
# zpool status -v host
pool: host
state: ONLINE
status: One or more devices are configured to use a non-native block size.
Expect reduced performance.
action: Replace affected devices with devices that support the
configured block size, or migrate data to a properly configured
pool.
scan: none requested
config:
NAME STATE READ WRITE CKSUM
host ONLINE 0 0 0
gpt/host0 ONLINE 0 0 0 block size: 512B configured,
4096B native
errors: No known data errors
# zdb host | grep ashift
ashift: 9
ashift: 9
But:
# sysctl vfs.zfs.min_auto_ashift
vfs.zfs.min_auto_ashift: 12
Of course, I’ve noticed this only after restoring all the backups, and getting
ready to put the box back into production.
Is this expected behaviour? I guess there’s no simple fix, and I have to start
over from scratch?
I had falsely assumed that vfs.zfs.min_auto_ashift would be 12 in all
circumstances. It appears when running FreeBSD 11.0p2 in VirtualBox, it can be
9. And my target disk was attached to the host and mapped into the VM as a
„native disk image“, but the 4k native sector size apparently got lost in that
abstraction.
The output above is with the disk installed in the target system with a native
AHCI connection, and the system booted from that disk.
I’ve certainly learned to double check the ashift property on creating pools.
The default value for vfs.zfs.min_auto_ashift is 9, so unless you
specifically set it to 12 you will get the behaviour you described.
Regards
Steve
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