Portable Hard Drives 
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| (1) | What is RAID?
RAID is an acronym for Redundant Array of Independent Disks. Today, most drives are relatively inexpensive and the meaning of the 'i' is changing into 'independent'. The purpose of RAID is to use 2 or more drives together in order to obtain increased performance and/or data security. |
| (2) | What types of RAID exist?
There are many different types of RAID modes. The RAID modes that are implemented in our line of RAID enclosures include the following: RAID 0 (Striping): Provides increased performance by writing alternating blocks of data (referred to as the stripesize) to 2 or more drivessimultaneously. Read performance is also improved since data is read from all drives at the same time. No redundant information is stored and failure of a SINGLE drive will cause all data to be lost. The number of drives in a RAID 0 array is sometimes also referred to as the stripe width. Total capacity is equal to the stripe width times the smallest drive. RAID 1 ( Mirroring): Provides redundancy by writing all data to 2 or more drives. RAID 1 provides no increase in write performance (it may even be a bit slower). Read performance tend to be faster than a single drive, but not as fast as RAID 0. RAID 1 provides excellent data security since ALL drives has to fail before any data is lost. Total capacity is equal to the smallest drive. RAID 5 (Striping with distributed parity): Data and parity is striped across 3 or more drives. Parity is distributed to each drive. RAID 5 is the most widely used RAID for servers and other high performance storage solutions. Any single drive can fail without data loss, ie. at least two drives must fail before any data is lost. Total capacity is equal to the number of drives minus 1 times the smallest drive. Benchmark Speed Test Results: eSATA | FW800 RAID 0+1 (Striping and Mirroring): Combines RAID 0 and RAID 1 by mirroring a striped volume. RAID 0+1 provides read and write performance very close (or equal) to RAID 0. RAID 0+1 should not be confused with RAID 1+0. If there is 1 mirror set, a single drive failure will cause the whole array to become, in essence, a RAID 0 array. RAID 0+1 requires an even number of drives and minimum 4. Total capacity is equal to the stripe width times the smallest drive. RAID 1+0 (Striping and Mirroring): Sometimes referred to as RAID 10, this mode combines RAID 0 and RAID 1 by striping a mirrored volume. RAID 1+0 has better data security than RAID 0+1. JBOD ( Just a Bunch Of Drives): Not actually RAID, 2 or more drives, which can be of any size, are recognized as separate drives by the OS. Since JBOD provides no performance increase and reduced data security, it is seldomly used. |
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| (3) | Why won't my computer recognize my 4TB or 8TB RAID system?
Windows 2000, XP & MAC OS 10.2 (& older) do not support partitions larger than 2TB. In order to support 2TB+ partitions, you must use Windows Vista, Windows 7, or Mac OS 10.3 or higher. Please note: Windows XP 64-bit and Windows 2003 support 2TB+ when using USB & eSATA, but are limited to 2TB when using FireWire. |
| (4) | How should I format my RAID system using Windows?
If the size of the RAID is greater than 2TB, the volume must be formatted using the GPT file system, which is not accessible by Windows XP 32-bit. |
| (5) | Does the RS-M2QO or RS-M4QO remain connected to the host computer and usable during the automatic mirror rebuild?
You still can access the data when the DataTale is rebuilding, but since it is rebuilding, the transfer speed will be slowed down. Please note: The typical rebuild time is 200GB per hour. |
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| (6) | How do RAID 5 and RAID 5+Hotspare differ from one another?
Under RAID 5, when one disk fails it must be replaced with a new disk. As soon as it is replaced, the automatic rebuild begins. Under RAID 5 + hotspare, when one disk fails, the automatically rebuild will begin immediately to the 4th spare drive. You can replace the failed disk with a new disk later and the new disk will then be the spare disk. Please note: RAID 5 utilizes 3 out of 4 disks, while RAID 5+Hotspare uses 2 out of 4 disks. |
| (7) | I am using a 2-bay DataTale in JBOD mode, the drives do not spin down when the computer enters sleep mode. Why?
The HDDs will not spin-down when it's connected via FireWire in JBOD mode. All other modes and connection methods work properly with the spin-down feature. |
| (8) | I want to install the 3 brand new drives in the RS-M4QO and configure to RAID 5+Hotspare. I want to leave the 4th slot empty so I can install a drive later. Can I do this?
To setup RAID 5 plus hotspare, you must install four hard disks in the beginning. The fourth disk will be initialized when the RAID 5 + hotspare is being formed. |
| (9) | I want to remove a drive from the RAID unit and install it in another enclosure for access to the files. How can I do so?
You can do so for RAID 1 operation. It is important to follow the correct procedure in order to get the data copied from the source HDD to the target HDD. |
| (10) | What eSATA ExpressCard do you recommend? For either Windows or Mac, we recommend Sonnet Tempo ExpressCard34, part # TSATAII-E342P.. |
| (11) | Can I change my RAID mode array after I have put data on it? The stripesize or stripewidth of a RAID 0, RAID 0+1, RAID 0+1, or RAID 5 array can't be changed without rebuilding the array. This will cause all data to be lost. |
