Resynchronizing A Raid 1 Or 5 Volume; Raid - ZyXEL Communications NSA-2400 User Manual

• Degraded when a volume is currently down, but can be fixed. Data access may be slower
from a degraded volume, so it's recommended that you replace the faulty disk and repair
the volume as soon as you can.
• Down when a volume is down and can not be fixed.
A down RAID volume cannot be used until you repair or replace the faulty disk(s) in the
volume. Degraded means one of the disks in the RAID volume is not available but the volume
can still be used. For a degraded volume, you should replace the faulty disk as soon as possible
to obtain previous performance. See your Quick Start Guide for more information on replacing
a disk. If there is already another volume resynchronizing, then you will see Waiting Resync
as the volume status.
If it's down, then the only indication is that they can no longer transfer files to/from the shares
in the down volume. If it's degraded, then file transfer to/from the shares in the degraded
volume will be slower.
There is no explicit message from CIFS that tells users their volume is
degraded or down.

7.3.3 Resynchronizing a RAID 1 or 5 Volume

Resynchronizing a RAID 1 or 5 Volume is done block-by-block, so the time it takes depends
more on the size of your hard drive(s) than the amount of data you have on them.
You should not restart the NSA while the NSA is resychronizing a volume as
this will cause the synchronization to begin again after the NSA fully reboots.
You can access data on a RAID volume while it is resychronizing, but it is not
recommended.

7.4 RAID

This section contains theoretical background on JBOD and the RAID levels used on the NSA-
2400. Skip to the next section if you already understand RAID and know what storage system
you want to use on the NSA-2400.
Redundant Array of Independent Disks (RAID) is a method of storing data on multiple disks
to provide a combination of greater capacity, reliability, and/or speed. JBOD (Just a Bunch Of
Disks) is not a RAID storage method but it is included in this discussion.
These are some terms that you need to know in order to understand storage systems.
NSA-2400 User's Guide
Chapter 7 Storage Screens
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