TowerSTOR TS4CT Introduction
Page 4
1.6.5 Disk Striping with dedicated parity (RAID 3)
The drives show up as one volume but the total capacity, depending on the drive with the smallest
capacity, is the combined size minus the size of one drive. RAID 3 uses byte-level striping with
parity data stored on a dedicated disk. The single parity disk is a bottle-neck for writing since every
write requires updating the parity data. One minor benefit is the dedicated parity disk allows the
parity drive to fail and operation will continue without parity or performance penalty. When one hard
drive fails, it can be replaced and the data rebuilt automatically.
Æ
3 drives
Æ
4 drives
Æ
3 1 spare
Spare Drive
When 3 hard drives plus 1 spare drive are used, the total capacity will only be as large as two
drives. When one drive fails, the data will be rebuilt immediately by using the spare drive, rather
than waiting for someone to replace the faulty one. To use a spare drive, install 3 drives, turn on
the device, set it to RAID 3, let it restart and then install the fourth drive.
1.6.6 Disk Striping with distributed parity (RAID 5)
The drives show up as one volume but the total capacity, depending on the drive with the smallest
capacity, is the combined size minus the size of one drive. RAID 5 uses block-level striping with
parity data distributed across all member disks and therefore provides the perfect balance between
high performance and data integrity. When one hard drive fails, it can be replaced and the data
rebuilt automatically.
Æ
3 drives
Æ
4 drives
Æ
3 1 spare
Spare Drive
When 3 hard drives plus 1 spare drive are used, the total capacity will only be as large as two
drives. When one drive fails, the data will be rebuilt immediately by using the spare drive, rather
than waiting for someone to replace the faulty one. To use a spare drive, install 3 drives, turn on
the device, set it to RAID 5, let it restart and then install the fourth drive.
Note
It is not possible to add more drives to an existing RAID array without re-formatting it. To add
additional drives at a later point, install the drive(s), change the RAID mode or re-confirm the
current mode and then create a new partition and format the drives again.
1.7 About Data Backup
To protect your files and help prevent the loss of your data, we strongly recommend that you keep
two copies of your data, one copy on your Hydra and a second copy either on your internal drive or
another storage media such as CD, DVD, Tape or an additional external drive.
Any loss or corruption of data while using the Hydra is the sole responsibility of the user, and under
no circumstances will the manufacturer be held liable for compensation or the recovery of this data.
