This is a simple tutorial about creating a RAID 1
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
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
. The performance of reading and writing increases because all the Heads are working all the timeRAID 1 - Mirroring,Duplexing
As 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 Parity
This 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 XOR
s every data written onto HDDs and stores in the Parity Disk. When one Disk fails, thet PD
ed 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 3
Similar to RAID 2
but instead of using Strips
which are in Bits
this technique uses Strips
. That increases the performance
. RAID 4
Strips data (Blocks) and uses a Parity Disk. Requires at least 3 Drives. Not widely used. RAID 5
The 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
Hope you would enjoy this tutorial.Thanks!
- 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.