FreeNASZFS

How to Disable Physical Sector Size Reporting on iSCSI Extent of FreeNAS

Sometimes, iSCSI clients do not accept physical sector sizes that is larger than 4KB. Luckily, FreeNAS has an option to work around it. It’s called Disable Physical Sector Size Reporting, which hide the physical sector size and therefore can force iSCSI clients to use the logical sector size, mostly 512 bytes.

On FreeNAS

Go to iSCSI Extents

Freenas Disable Physical Block Size Reporting 00
Freenas Disable Physical Block Size Reporting 00

Edit Extents

Freenas Disable Physical Block Size Reporting 01
Freenas Disable Physical Block Size Reporting 01

Check Disable Physical Sector Size Reporting on

Freenas Disable Physical Block Size Reporting 02
Freenas Disable Physical Block Size Reporting 02

See Results

Freenas Disable Physical Block Size Reporting 03
Freenas Disable Physical Block Size Reporting 03

Don’t forget to restart iscsi service.

On iSCSI Initiators

Rescan iSCSI Targets

[root@primary01 ~]# iscsiadm -m node -p nas --rescan
Rescanning session [sid: 1, target: iqn.2005-10.org.freenas.ctl:asm-t1, portal: 192.168.15.101,3260]
Rescanning session [sid: 2, target: iqn.2005-10.org.freenas.ctl:asm-t2, portal: 192.168.15.101,3260]

See Results

[root@primary01 ~]# fdisk -l /dev/sdb1

Disk /dev/sdb1: 17.2 GB, 17178820608 bytes, 33552384 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 16384 bytes / 1048576 bytes

We’re done!

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