I'm attempting to connect my desktop (running debian 7) to a QNAP NAS (running QTS 4.1.1) using iSCSI with an MTU=9000. The network infrastructure consists of a cat5e crossover cable between the desktop and the nas.
If I set the MTU on local machine and iSCSI machine to either 1500, 4074, or 7418 everything works fine.
However, if I set MTU to 9000 and issue the same mount command as before then it mounts as a read only filesystem:
mount /dev/sdc1 /mnt/iscsi
After that command is issued, the output of mount -l is:
/dev/sdc1 on /mnt/iscsi type ext4 (rw,relatime,user_xattr,barrier=1,data=ordered)
However as soon as I try to write to the filesystem I receive an error Read-only file system and the output of mount -l becomes:
/dev/sdc1 on /mnt/iscsi type ext4 (ro,relatime,user_xattr,barrier=1,data=ordered)
I've tried mounting with -w and -o rw but neither have any effect. Does anyone have any suggestions on what might be causing this?
I know the nas supports jumbo frames, but could it be that the NIC doesn't support them? Is there any way to check?
