(Difference between revisions)
(added introduction) |
m |
Revision as of 16:38, 24 July 2008
Introduction
Recently, our group purchased a Sans Digital MOBILESTOR MS2UTN+ two-disk external hard drive enclosure and two 750 GB 7500rpm SATA Samsung Spinpoint F1 internal hard drives to back up one of the servers. The enclosure (shown in Figure 1) has a built in RAID controller with the following storage modes:
- BIG (not RAID 0): Concatenates the disks to create one large virtual volume. It isn't actually striping the data across the two disks so it will not result in faster performance. I suggest avoiding this. Total storage = 1.5 TB.
- JBOD (Just a Bunch of Disks): Both hard drives are completely separate. Your computer will see it as two separate external hard drives if you use USB, or if you have port multiplier (PM) support for SATA. If one drive fails the data on the other is still intact. Total storage = 1.5 TB.
- FAST (RAID 0): Data is striped across both disks to create one drive with twice the original storage. Using both drives to access data greatly improves read/write performance compared to that of a single physical drive. However, if one drive fails all the information is lost. Total storage = 1.5 TB.
- SAFE (RAID 1): Data is stored on both disks to create exact copies of each other. Data is not lost if only one drive fails; the broken drive can be replaced and the new drive can be mirrored off of the remaining one. Total Storage = 750 GB.
- SAFE 33 (33% RAID 1, 66% RAID 0): 33% of each disk is used for redundant storage using RAID 1, while the remaining is striped using RAID 0. Requires PM for SATA. Total Storage = 250 GB RAID 1, 1.0 TB RAID 0.
- SAFE 33 (33% RAID 1, 66% RAID 0): 50% of each disk is used for redundant storage using RAID 1, while the remaining is striped using RAID 0. Requires PM for SATA. Total Storage = 375 GB RAID 1, 750 GB RAID 0.
- GUI: Any of the above modes can be selected and changed using the GUI provided with the RAID controller (Silicon Image SteelVine 57XX series). This is available for download from either Sans Digital or Silicon Image.
The desired storage mode can be selected/changed via the knob on the back of the enclosure and pressing the reset button shown in Figure 2 (warning: any data on the disks will probably be lost).
