An IP-based (Internet Protocol) storage networking standard called iSCSI (Internet Small Computer System Interface) is used to connect data storage facilities. iSCSI enables location-independent data storage and retrieval across LANs (Local Area Networks) and WANs (Wide Area Networks) by transmitting SCSI commands over IP networks.
Clients like PCs, servers, and virtual machines can use the storage from your QNAP NAS as virtual disks thanks to iSCSI. Virtual disks can be used as backup locations or for additional storage by clients, who can partition, format, and use them just like local drives.
Important :
An iSCSI LUN is a section of storage that initiators can use by attaching it to a target. There are two kinds of LUNs available in QNAP.
Block-based LUNs uses space from storage pool.
File-based LUNs uses space from volume.
Generally, block-based LUNs should be used instead of file-based LUNs, it support more snapshot & virtualization features.
A Comparison of Block-based and File-based LUN Features
| Feature Name |
Block-Based LUN |
File-Based LUN |
| VAAI Full Copy |
✓ |
✓ |
| VAAI Block Zeroing |
✓ |
✓ |
| VAAI Hardware Assisted Locking |
✓ |
✓ |
| VAAI Thin Provisioning and Space Reclamation |
✓ |
x |
| Thin provisioning |
✓ |
✓ |
| Space reclamation |
✓
Supported in: VMware ESXi with VAAI, Windows Server 2012 or later, Windows 8 or later |
x |
| Microsoft ODX |
✓ |
x |
| LUN Import/Export |
✓ |
✓ |
| LUN snapshots |
✓ |
You must take a snapshot of the parent volume. |
