User`s guide

Synology NAS User's Guide
Based on DSM 5.0
26 Chapter 5: Manage Storage Space
Expand a Volume or Disk Group by Adding Disks
For SHR, JBOD, RAID 5, RAID 5+Spare, and RAID 6, the storage capacity of volumes and Disk Groups can be
expanded by adding more hard disks if there are empty hard drive bays in your Synology NAS. For more detailed
instructions, please see DSM Help.
Please see the following table regarding the minimum size of new hard disks.
RAID Type Minimum Hard Disk Size
SHR
The capacity of the hard disk you wish to add must be equal
to or larger than the largest hard disk in the volume or Disk
Group. For example, if your volume is composed of three
hard disks – 2 TB, 1.5 TB, and 1 TB respectively – then the
capacity of the new hard disk must be at least 2 TB.
RAID 5, RAID 5+Spare, or RAID 6
The capacity of the hard disk you wish to add must be equal
to or larger than the smallest hard disk in the volume or Disk
Group. For example, if your volume is composed of three
hard disks – 2 TB, 1.5 TB, and 1 TB respectively – then the
capacity of the new hard disk must be at least 1 TB.
Data Scrubbing
Data scrubbing is a data maintenance function that inspects volumes or Disk Groups and repairs any detected
data inconsistencies. This function can be used with volumes or Disk Groups that implement SHR (comprised of
three or more disks), RAID 5, or RAID 6.
We recommend regularly performing data scrubbing in order to maintain data consistency and avoid losing any
critical data in the event of disk failure. For detailed instructions, please see DSM Help.
SSD TRIM
If a volume consists entirely of SSDs (Solid State Drives), we recommend enabling SSD TRIM. This feature
optimizes the read and write performance of volumes created on SSDs, increasing efficiency as well as
extending the lifetime of your SSDs.
Before trying to set up SSD TRIM, please see DSM Help for detailed instructions and more limitations.
Note:
 SSD TRIM is only available on certain Synology NAS models and RAID types.
 Some SSD models are not able to perform SSD TRIM on RAID 5 and RAID 6 volumes. Please refer to the
compatibility list at www.synology.com.
iSCSI Targets and LUNs
iSCSI (Internet Small Computer System Interface) is a type of storage area networking (SAN) service that
provides access to consolidated, block level data storage. The main use of iSCSI is to facilitate data transfers
over intranets, allowing users to manage storage over long distances.
The sections below provide basic information regarding iSCSI Targets and LUNs. For more detailed instructions,
please see DSM Help.
Manage iSCSI Targets
Go to Storage Manager and click the iSCSI Target tab to manage iSCSI Targets on your Synology NAS. The
maximum number of iSCSI Targets varies depending on the model. For more information, please refer to
“Manage iSCSI LUNs”.