Good day!
I test NAS in iSCSI mode.
When I create ISCSI LUN block-based at RAID 5 (8 HDD), I receive good IOPS in VDBench 4k random read.
But when I create same size LUN as file in NAS, same test gave results about 35000 IOPS (Random read, 4k).
I tryed QNAP dual Xeon-based NAS (EXT4) and Synology dual Xeon based NAS (Btrfs), and both of them has same situation:
Block-based iSCSI LUN gave IOPS equals number of HDDs multiplied by IOPS of every HDD (often 800-1200 in random read 4k).
But file-based iSCSI LUN gave 30-40k IOPS, which is much more larger then expected.
At same time, IOMeter gave right results for both block-based LUNs and file-based LUNs for iSCSI (800-1200 IOPS in random 4k).
How should I tune VDBench to achieve right IOPS in file-based iSCSI LUNs?
Thank you