1. What is RAID?
2. What types of RAID exist?
3. Why won't my computer recognize my 4TB, 6TB or 8TB RAID system?
4. How should I format my RAID system?
5. Does the RS-M2QO or RS-M4QO remain connected to the host computer and usable during the automatic mirror rebuild?
6. How do RAID 5 and RAID 5+Hotspare differ from one another?
7. I am using a 2-bay DataTale in JBOD mode, the drives do not spin down when the computer enters sleep mode. Why?
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?
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?
10. What eSATA ExpressCard do you recommend?
11. Can I change my RAID mode array after I have put data on it?
12. I have an RS-M4QO enclosure. Can I move the drive set from this unit to the RC-M4QJ and have it recognize the drive set automatically?
13. I have a 2-Bay RS-M2QO RAID set for Mirror (RAID 1) mode. What is the procedure for removing a drive and installing a new drive so that the data will copy to the new drive?
    

RAID is an acronym for Redundant Array of Independent Disks. The purpose of RAID is to use 2 or more drives together to obtain increased performance and/or data security and redundancy.

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.

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. 

SPAN (Large) : Spanning combines multiple hard drives into a single logical unit. Unlike Striping, Spanning writes data to the first physical drive until it reaches full capacity. When the first disk reaches full capacity, data is written to the second physical disk. Spanning provides the maximum possible storage capacity, but does not increase performance or safety.

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.

We strongly recommend performing a Low Level Format of the entire volume after configuring the RAID mode. This will write zeroes to all sectors of the RAID and define where the tracks and sectors of the RAID are located, which will result in optimal performance. To perform a low level format using Windows, we suggest EaseUs Partition Tool and choose the Wipe Partition option, which performs a Low Level Format.

To perform a Low Level Format using Mac OSX, please do the following:

1. Configure the RAID and connect it to your Mac.
2. Open Disk Utility. (Applications folder > Utilities > Disk Utility). From the list on the left, click on the external RAID with the size in GB (not the indented item underneath).
3. Click the 'Erase' tab at the top of the application.
4. Select the drop down menu under 'Volume Format' and select Mac OS Extended (Journaled).
5. Click 'Security Options' and select 'Zero Out Data'. Click Ok
6. Click 'Erase'. You will be presented with an 'Are you Sure' dialog.
7. Click 'Erase' to perform a Low Level format of the RAID volume.

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 150GB to 200GB per hour.

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.

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.

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.

You can do so for RAID 1(Mirroring) operation. It is important to follow the correct procedure in order to get the data copied from the source HDD to the target HDD.

What eSATA ExpressCard do you recommend?

For either Windows or Mac, we recommend Sonnet Tempo ExpressCard34, part # TSATAII-E342P or Sonnet Tempo Pro ExpressCard32, part # TSATAII-PRO-E34.

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.

I have an RS-M4QO enclosure. Can I move the drive set from this unit to the RC-M4DJ and have it recognize the drive set automatically?

No, the RS-M4QO and RC-M4DJ (or RS-M2QO) are independent to each other, and every RAID system will initialize the HDD before the RAID mode is applied.

I have a 2-Bay RS-M2QO RAID set for Mirror (RAID 1) mode. What is the procedure for removing a drive and installing a new drive so that the data will copy to the new drive?

Disconnect (eject) the RAID system from the computer. Do NOT power the RAID unit off. Remove (hot-swap) an existing HDD and install a new HDD in the empty slot (the new HDD does not need to be formatted). The RAID system will initialize the new HDD, and consider the existing HDD as “source” and newly inserted HDD as “target” to auto-rebuild data. Note: If the user powers off the RAID unit, then removes one of HDD, then inserts the new HDD, then powers on RAID unit, the RAID unit will initialize both HDDs.