User Manual

Synology NAS User's Guide

Based on DSM 6.2

33 Chapter 6: Manage iSCSI Service

Manage iSCSI LUNs

An iSCSI LUN (logical unit number) represents an individually addressable portion of an iSCSI Target. An iSCSI

LUN can be mapped to multiple iSCSI Targets to perform storage operations such as read or write.

Go to iSCSI Manager and click the LUN tab to manage iSCSI LUNs on your Synology NAS. The maximum

number of iSCSI LUNs varies depending on the model. For more detailed instructions and limitations, please see

DSM Help.

LUN Types

A volume must be created first in Storage Manager before you create a LUN. Synology NAS currently provides

the following LUN types:

 LUNs with new Advanced LUN features, which support instant snapshots.

 LUNs with Thin Provisioning, including LUNs with legacy Advanced LUN features.

 LUNs without Thin Provisioning; may have better performance in most cases.

Important: Only LUNs with new Advanced LUN features support instant snapshots. This type of LUN must be

created on Btrfs volumes and are available in DSM 6.2 onwards.

Take iSCSI LUN Snapshots

A snapshot of an iSCSI LUN is a point-in-time, read-only copy of an iSCSI LUN. It is efficient for your valuable

storage space and also increases the level of protection, letting you easily restore valuable data.

Go to iSCSI Manager and click the Snapshot tab to take iSCSI LUN snapshots. For more detailed instructions,

please see DSM Help.

iSNS (Internet Storage Name Service) provides the mechanism for centralized management. You can register all

the iSCSI Targets with an iSNS server at iSCSI Manager > Settings.

Set I/O Queue Depth

I/O queue depth determines the maximum number of iSCSI commands that can be sent to the queue during

each iSCSI session. A longer queue depth may help enhance throughput in 10/40 GbE network and SSD

environments. Queue depth set as 1 may help with latency or stability issues. Go to iSCSI Manager > Settings

to set the I/O queue depth according to your needs.