In today's data intensive environment it is more important than ever to backup your data.  And in today's hardware environment we have super fast processors and large amounts of memory.  The slowest parts in most modern PCs are typically your hard drives.

This issue has been around for many years, but today leveraging your hard drives for extra speed is very useful.  There are 3 common raid setups that are used often.  The first, Level 0, is two drive that the data is spread across and is the fastest of the three styles.  This kind of setup uses the speed of both drives at the same time.  However there is absolutely no data security, if one of the two drives fails in most cases all the data on the raided drives is lost.  This setup is most commonly used for gaming PCs where raw speed is the most important issue.  RAID level 0 gives you access to the full space of both drives and treats the two drives as one large drive inside of Windows.

Raid level 1 is the most common simple raid.  This is commonly referred to as mirroring.  As the nickname suggests, the data is copied automatically to each of the hard drives.  Each drive has a exact copy of the data.  You need two drives to do this setup and when setup have the amount of usuable space of the smallest drive.  However in almost all cases the exact same hard drive sizes should be used.  For data security and recovery this is one of the most secure forms of raid.  Read times from a RAID 1 are typically very good as both drives are leveraged.  Write times can sometimes be an issue as the data is wrote twice, once to each drive.  But rarely do we see issues with the write times as hard drives these days keep up rather well.  From experience we have found that the much more expensive RAID edition hard drives handle this type of setup much better.  They are designed for this type of work and tend to be much more stable.  For environments that have a very large amount of data that needs the speed of raid level 0 and the security of mirroring, RAID level 10 is a combination of these two styles of raid. RAID level 10 is very expensive hardware wise as it does require a minimum of 4 hard drives to create.

The last common raid level is RAID level 5.  Raid level 5 requires a special raid card and a minimum of 3 hard drives.  It is very common to see RAID 5 setups with 4-6 hard drives.  These are typically identical hard drives.  When the RAID is setup you end up with about 2/3rds of the total drive space of all the drives as usable space.  The rest of the space on each drive is reserved for "parity".  Parity is data that is distributed from the other drives that contains the other drive's data.  Should one of the drives in the array fail the parity is used to rebuild the failed drive.  It is the leveraging of the space on all the drives which is why this is a very common raid format.  You can have 10 hard drives in a raid 5, the data to rebuild each drive is then distributed accross all 10 drives.  The idea is the more drives the less chance of failures.  It is not common but if you had 2 of 4 drives in a RAID 5 fail at the same time, you could lose all the data on the group of drives.   RAID 5 has its benefits but one of its largest drawbacks is that if the array does fail it can be very difficult to retrieve that data.   Read and write access times are very well balanced in a RAID 5 also.  Read times are superb.  Write times can be slow but most modern raid cards have dedicated memory and some have their own processor to manage this process.

Important to consider when using a RAID in a business enviroment is backups still.  Having a spare raid card come in handy should your raid card fail.  Most raid cards use their own little format for controlling the hard drives, so you can not just throw a different brand or chipset card in and expect it work again.  Most RAID cards also support a "hot spare" hard drive.  Which is a spare drive in the system that is automatically moved to once a hard drive failure occurs.  But most important to consider is that your normal everyday backups still need to happen.  We have seen raids fail and it can be a disaster if not planned for.  A simple and inexpensive form of backup these days is Carbonite or Mozy online backup services.  For simpe PCs they have unlimited data plans for as little as a few dollars a month.  So cost is not really an issue these days.

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