iSCSI lu_disk_write() failed

[karim]

Hi,

I tested. FreeNAS-9.2.1.6-RELEASE-x64
I tested. FreeNAS-9.2.1.7-RELEASE-x64

I have created a virtual machine under vmware wks with 4gbx36 disks (excluding boot disk)
Created a single z2 volume with all disks
pool size 62.5gb, available 62.5gb

then created a 45gb iSCSI zvol (~74%), pool available 16.1gb
screenshot: attachment #1

connected to windows with iSCSI
screenshot: attachment #2

started copying files
screenshot: attachment #3

when copied data reached 20gb, the available and total size started to decrease fast (is total size decrease a bug?), used is still the same.
screenshot: attachment #4

when copied data reached 25gb freenas started give errors and copying stopped.
screenshot: attachment #5

and this is after freenas power off/on.
iscsi zvol shows the used/empty space correct but when tried to copy files freenas gives errors again as in previous ss #5
screenshot: attachment #6

any help appreciated

 

[cyberjock]

Not sure exactly what happened. But, you shouldn't be creating iscsi zvols that are >50% of a pool. At generation they will be the largest avaialble block size, and they are likely to only get smaller as time goes on. This increases overhead for the file system.

Unfortunately there's 2 things at work. zvol has it's own metadata and needs, and the pool has it's own metadata and needs. The two are intertwined to some extent and "taking from one gives to the other".

I can't provide much more than that as there's far more at work than just free and used disk space. But creating a zvol that is already at 74%, especially at such a small size, is not a good way to test iSCSI.