This is a simple tutorial about creating a
RAID 1 in
VMware for IT people.
VMware, well I think you know already about
Server Virtualization.Its a well known product.
Let's discuss about some of the techniques related to
Load Balancing or
Fault Tolerance.....The Disks here used are
Dynamic Disks.
RAID - Reduddant Array of Independant (Not much
Inexpensive these days. That term suites no more)
Disks. There are two types of RAID:
- Software RAID - Implemented via the OS or with the help of a Software. Not much efficient however.
- Hardware RAID - Hardware level RAID. Much more efficient and Fault Tolerant.
The idea to use a set of disks or an array is to increase the performance (Load balancing) and provide Disaster Recovery (Folt Tollerant).
RAID 0 - StripingThe fastes of all the RAID configurations. This is known as
Striping.
Striping is the process of Writing data Sequentially to or Read from more than a single Hard Drive (or a Storage Device).First the data is broken up into chunks or blocks. Then the writing process will be accomplished. The process of writing will be done
Simultaneosly onto
Strips. The performance of reading and writing increases because all the Heads are working all the time
RAID 1 - Mirroring,DuplexingAs the name implies, it creates a
Mirror of one
Disk onto another. Data will be written to Both the Disks. So if one disk fails other one can be mounted or it can be used to
Restore data.There can be a deadlock how ever. The
Disk Controller.
RAID 1 uses a
Single Disk Controller thus a
Single point of failure.We can avoid this easilly with the use of
Disk Duplexing which means usage of
2 Disk Controllers.
RAID 2 - Striping with ParityThis is similar to RAID1 but with an added feature known as
Parity. One disk - typically the last one - is used to store somethings called Parity bits. With the use of these Parity Bits, the lost data can be easilly generated. This uses
Logical XOR Operation. When writing, it
XORs every data written onto HDDs and stores in the Parity Disk. When one Disk fails, thet
PD is
XORed with other Data bits on the functioning Hard Drives. This is a very effective technology in terms of
Fault Tolerance. But
Performance is pretty low.
RAID 3Similar to
RAID 2 but instead of using
Strips which are in
Bits this technique uses
Strips in
Bytes. That
increases the performance over
RAID2.
RAID 4Strips data (Blocks) and uses a Parity Disk. Requires at least 3 Drives. Not widely used.
RAID 5The most popular method. Requires at least 3 Disks. Disks are used to store Parity data as well for each perticular drive.
Data Stiped in Bytes (uses block-level striping with parity).
Supports Unlimited number of Drives.
Failure rate Drops when the number of devices increas.High speed reads can be performed. But writing is pretty slow in this approach.
Note:
The non-standard RAID levels 5E, 5EE and 6E extend RAID 5 and 6 with hot-spare drives. Other non-standard RAID levels include: RAID 1.5, RAID 7, RAID-DP, RAID S or parity RAID, Matrix RAID, RAID-K, RAID-Z, RAIDn, Linux MD RAID 10, IBM ServeRAID 1E, unRAID, and Drobo BeyondRAID.
So how are we going to implement such a structure in
VMware?That is quite easy. This is an example of Disk Mirroring. Each disk has to have Similar Capacity.
- Click on "Edit Virtual Machine Settings".
- Click on Add ->Next-> Create new Hard Disk.
- Select SCSi.
- Give a Suitable Disk Capacity for new Disk.
- Give a "Name" and Browse the storage location.
- Click on Finish.
- You have to Repeat the steps to create the number of Disks that you require. You have to have 2 Disks. Do not use the Main Drive. Use Separate Disks.
- Click on OK.
- Click on "Power on this Virtual Machine".
- After booting up the machine, its the time to implement the Mirrors.
- Log in.
- Right click on My Computer and select "Manage".
- Click on "Disk Management".
- Get the "Convert Disk Wizard".
- Select the 2 disks (tick on the check boxes).
- Click "Next -> Finish
- Right click on the Disk n which your first added drive (n = the number).
- Select "New Volume".
- Select the option "Mirrored".
- Click on "Next".
- Add the Disks from the left hand list box to the right hand list box (the two drives that you have created).
- Click on "Next".
- Assign a Drive Letter.
- Format using NTFS. Make sure you provide a "Volume Label".
- That's all what you need to do!
- Wait until the Volumes get formatted and Synchronize.
- Implementation of the other technologies are similar to the above procedure.
Hope you would enjoy this tutorial.Thanks!
-Lasitha
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