zvol block size?

[mleopold]

hi,

i have freenas box with 4 disks in RAID10 for storage.
these disks have a sector size of "logical 512, physical 4096, offset 0" (as reported by "camcontrol identify").

i'm creating zvols for iSCSI. these are by default created with a "block size" of 16K. when i create extents for iSCSI i choose a "logical block size" of 4K. this is the same 1/4 logical/physical ratio as on the physical disk.

fdisk on linux clients that use these iSCSI devices says "The device presents a logical sector size that is smaller than the physical sector size."

does it make sense what i am doing? should i be using 4k for zvol block size, so physical and logical block size match for the client? my use is case is creating storage for KVM.

thanks for reading and (maybe) explaining this (again) to me
matthias

 

[bigphil]

On your iSCSI extent in FreeNAS, check the box to "disable physical block size reporting." That should correct the issue.

 

[DMooring]

I would like an answer to the question myself. I am setting up iSCSI storage now for vSphere. Would it run better if they both where 4k or 16k or does it not matter much?