Whitepaper: ReadyNAS FlexRAID Volume Optimization Guide

Whitepaper:
Optimizing Your ReadyNAS® OS Flex-RAID Volumes
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ReadyTIER assembles the SSDs into their own RAID configuration. That configuration depends on both the number of SSDs
and the RAID configuration of the volume. The following table shows what those combinations are.
RAID/VOLUME Configuration SELECTED (SSD) DRIVES ReadyTIER RAID Configuration
RAID 0 1+ RAID 0
RAID 1 2 RAID 1
RAID 1 3+ RAID 5
RAID 5 2+ RAID 5
RAID 6 2 RAID 1
RAID 6 3 RAID 5
RAID 6 4+ RAID 6
RAID 10 2+ RAID 10
RAID 50 ANY BLOCK
RAID 60 ANY BLOCK
11.8. Global Spares
Prior to ReadyNAS OS 6.7, unused disks were available for
use in both new volumes and existing volumes (if a disk in
a volume failed, known as being a global spare). Starting in
OS 6.7, you can specifically designate disks as global spares.
If a disk in a volume fails, ReadyNAS OS first tries to use a
designated global spare to rebuild the damaged volume. If
no designated global spares are available, the system uses
any hot, unused disks as replacement.
Global spares show as green-colored drives. To add a global
spare to an existing volume, select the volume, select the
drives you wish to allocate as explicit global spares, and then
click on the Global Spare button.