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Raid Arrays

Although not directly connected with any of our existing business Daniel (CB and C2-Cine  IT Support Engineer) and I have been investigating Raid Arrays as a low cost alternative to a SAN for use with video scanning and/or multitrack audio. We tested the external eSATA Raid Arrays on two very different computers.

External Raid Box:
StarTech 3.5in eSATA 4-Bay Raid Enclosure, supplied with its own eSATA interface card.
Throw away the supplied eSATA interface as it has a maximum transfer speed of 60MBytes/Sec. Provided your computer supports SATA then a  eSata cable costs about £6.
Raid Drives:
Four 2TB drives, as our primary interest was in recording and playing back raw video files we selected low power 5400 rpm drives which work better for this application. Sur 

Test Computer 1
AMD Six core 3GHz 1075T, Asus Crosshair III Formula Motherboard, running 64 Bit Windows 7, this machine has 4GB of 1600 Memory and a ATI 4850 video card. The computer supports internal software RAID and has an ESata port

External Raid using 2 x 3.5" 2TB drives in Raid 0 speed approx 180MByte/Sec, There was no advantage in using 3 or 4 drives.

Single 2.5" enclosure with eSATA and USB
USB-2 about 32MByte/Sec
ESata Limited by 2.5" drive speed to about 80MBytes/Sec

Test Computer 2
Toshiba Tecra M10: Two core 2.6GHz Centrino running 32 Bit Windows XP, this machine has 3GB or Memory and is fitted with an ESata Port
Note: XP Maximum partition size is 2TB


External Raid using 2 x 3.5" 2TB drives in Raid 0 speed approx 180MByte/Sec, There was no advantage in using 3 or 4 drives.


Single 2.5" enclosure with eSATA and USB
USB-2 about 32MByte/Sec
ESata Limited by 2.5" drive speed to about 80MBytes/Sec

A few brief conclusions on current setup
1) The processor made little difference to the disc access speed
2) External eSATA Raid drives show no improvement with more than 2 drives
3) If Running XP only then remember the 2TB partition limit
4) Use eSATA not USB-2, I will be checking USB-3 later
5) For hi speed disc access we are looking at internal raid with the drives mounted in caddies
6) If you must use an external raid then use Mini-SAS
7) Our next test will be to compare the built in software motherboard raid with a hardware raid card