Back It Up or Risk Losing It

Ever wonder what will happen if one day a tsunami come and hit your data centre? With no back up done or maybe your back up is also swept away by the currents? What will you do then? Many things in life are unexpected, and preparing for it is one of the most essential things you will need to do.

Redundancy is a word not allowed in the world of back ups and keeping your business afloat. If you lose your data (imagine credit card information, customer details and invoices) to a minor fault that hits your server, what will happen? Chances are you will lose a lot of money. In this article, we’ll discuss the methods of backing up data and what perils it holds for us.

This will apply to almost anyone owning a dedicated server or two; shared accounts maybe applicable for some techniques, but not all.

RAID, or Redundant Array of Independent Disks, is a technique of applying 2 or more hard disk running simultaneously, one mirroring the other to create a back up in case the other fails.

There are a few types of RAID which you should take note:

• Level 0 -- Striped Disk Array without Fault Tolerance: Provides data striping (spreading out blocks of each file across multiple disk drives) but no redundancy. This improves performance but does not deliver fault tolerance. If one drive fails, then all data in the array is lost.

• Level 1 -- Mirroring and Duplexing: Provides disk mirroring. Level 1 provides twice the read transaction rate of single disks and the same write transaction rate as single disks.

• Level 2 -- Error-Correcting Coding: Not a typical implementation, and rarely used, Level 2 stripes data at the bit level rather than the block level.

• Level 3 -- Bit-Interleaved Parity: Provides byte-level striping with a dedicated parity disk. Level 3, which cannot service simultaneous multiple requests, also is rarely used.

• Level 4 -- Dedicated Parity Drive: A commonly used implementation of RAID, Level 4 provides block-level striping (like Level 0) with a parity disk. If a data disk fails, the parity data is used to create a replacement disk. A disadvantage to Level 4 is that the parity disk can create write bottlenecks.

• Level 5 -- Block Interleaved Distributed Parity: Provides data striping at the byte level and also stripe error correction information. This results in excellent performance and good fault tolerance. Level 5 is one of the most popular implementations of RAID.

• Level 6 -- Independent Data Disks with Double Parity: Provides block-level striping with parity data distributed across all disks.

• Level 0+1 – A Mirror of Stripes: Not one of the original RAID levels, two RAID 0 stripes are created, and a RAID 1 mirror is created over them. Used for both replicating and sharing data among disks.

• Level 10 – A Stripe of Mirrors: Not one of the original RAID levels, multiple RAID 1 mirrors are created, and a RAID 0 stripe is created over these.

• Level 7: A trademark of Storage Computer Corporation that adds caching to Levels 3 or 4.

• RAID S: EMC Corporation's proprietary striped parity RAID system used in its Symmetrix storage systems.

The most common method of RAID is RAID 1 and 5 configurations.

You should never rely on RAID alone to do the back up for you, since if the RAID drives should fail, or corrupted, the mirrored files will also follow suit.

The other way to create back ups is through the use of magnetic tapes. You can configure it to be backed up in intervals of daily, weekly or monthly. There is a problem with this type of back up however. Over time, tapes will deteriorate in its conditions because of the weather and other unforeseen circumstances, and what will become of your valuable data?

Recovering lost data from tapes can prove to be a gruelling task too. They take up valuable system resources and bogged down the server. Furthermore, it is a time consuming task.

You can have them transferred into a CD or DVD medium. But this method itself is also riddled with problems. CDs can be scratched, maybe not by yourself, but over the period of time, the constant moving and even dust can scratch the surface of the CDs, making sensitive data unreadable.

Some hosting companies however, supply a service in which they will help you copy data from your server to another server of theirs. This method is costly and may not be justifiable in it’s implementations. Of course, the upside is that you get to rest assure in it’s reliability and restoring data is pretty quick, provided the back up is within the same data centre. You can even use CRON scripts in helping you do the back ups.

To conclude, it is not really advisable to depend on only one type of back up to safeguard your data. Utilize a number of methods to keep yourself away from the trouble on a later date. Go with a tape back up and RAID or CD/DVD with a mirroring server backup or any other combinations.