about zfs and ashift and changing ashift on existing zpool

Eugene Grosbein eugen at grosbein.net
Tue Apr 9 00:22:31 UTC 2019

09.04.2019 7:00, Kevin P. Neal wrote:

>> My guess (given that only ada1 is reporting a blocksize mismatch) is that
>> your disks reported a 512B native blocksize.  In the absence of any override,
>> ZFS will then build an ashift=9 pool.


> smartctl 7.0 2018-12-30 r4883 [FreeBSD 11.2-RELEASE-p4 amd64] (local build)
> Copyright (C) 2002-18, Bruce Allen, Christian Franke, www.smartmontools.org
> Vendor:               SEAGATE
> Product:              ST2400MM0129
> Revision:             C003
> Compliance:           SPC-4
> User Capacity:        2,400,476,553,216 bytes [2.40 TB]
> Logical block size:   512 bytes
> Physical block size:  4096 bytes

Maybe it't time to prefer "Physical block size" over "Logical block size" in relevant GEOMs
like GEOM_DISK, so upper levels such as ZFS would do the right thing automatically.

More information about the freebsd-stable mailing list