ioSafe NAS User's Guide
Based Synology on DSM 5.0
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Hard Disk Requirements
In order to change the RAID type of a volume or Disk Group, there must be a sufficient number of available hard
disks installed in your IoSafe NAS. Please see below for the minimum number of hard disks required for each
RAID type.
RAID Type
Minimum Hard Disks
RAID 1
2 or 4
RAID 5
3
RAID 5+Spare
4
RAID 6
4
Expand Volumes or Disk Groups
The storage capacity of volumes or Disk Groups can be gradually expanded by installing more or larger hard
disks. This feature allows you to expand the capacity of your volume or Disk Group according to your budget and
with no need to worry about losing any existing data.
The sections below provide basic information regarding expanding volumes and Disk Groups. For more detailed
instructions, please see
DSM Help
.
Expand a Volume by Changing Volume Size
When creating multiple volumes on RAID, specified amounts of Disk Group storage capacity can be allocated to
each volume. If you want to change the amount of allocated storage capacity for a volume, please select the
volume and click
Edit
.
Expand a Volume or Disk Group by Replacing Hard Disks
For SHR, RAID 1, RAID 5, RAID 5+Spare, or RAID 6, the storage capacity of volumes and Disk Groups can be
expanded by replacing smaller hard disks with larger ones. When expanding storage capacity with this method,
please be careful to replace each hard disk one-by-one. After replacing one hard disk, the volume or Disk Group
must be repaired before the next hard disk is replaced. For more detailed instructions, please see
DSM Help
.
Please see the following table to see which hard disk should be replaced first.
RAID Type
Minimum Hard Disk Size
RAID 5 and RAID 6
When replacing hard disks of RAID 5 or RAID 6 volumes or
Disk Groups, the smallest hard disk should always be
replaced first. The storage capacity of RAID 5 volumes is
(number of hard disks – 1) x (smallest hard disk size), and
RAID 6 is (number of hard disks – 2) x (smallest hard disk
size). Therefore, the smallest hard disk should always be
replaced first in order to maximize hard disk usage.
SHR (Synology Hybrid RAID)
If the capacity of all member hard disks is equal, then you
should replace at least two hard disks. Otherwise, the
capacity of your volume will not expand.
If the capacity of member hard disks is different, then the
new, replacement hard disks should be equal to or larger
than the largest existing hard disk. In addition, you should
replace smaller member hard disks first in order to optimize
capacity usage.
