When you purchase a dedicated server, there is an addon option (sometimes free and sometimes chargeable) called RAID. It is basically a hard disk array configuration which explains how your data is stored. Wikipedia has a very comprehensive, though lengthy, explanation about RAID but here’s a summary of what’s most applicable to most Malaysian SMEs.
There are six types of RAID, though only two types will be useful to most of us. For illustration, let’s assume your dedicated server has 2 hard disk drives – HDD A and HDD B:
1) RAID 0
In RAID 0, data is evenly striped across the hard disks. Say you upload a 500MB file to your server – 250MB will be copied to HDD A and 250MB to HDD B.
RAID 0 has better performance since data is read/written simultaneouly across the hard disks. It can be created with different hard disk sizes but is limited to the size of the smallest hard disk. For example, if HDD A is 1TB and HDD B is 1.5TB, your total usable disk space is 1TB.
This array is used for when high performance is required, e.g. gaming server.
2) RAID 1
In RAID 1, data is mirrored across the hard disks. Say you upload a 500MB file to your server – two exact copies will be created on HDD A and HDD B respectively.
RAID 1 is for those who places priority on reliability. In this array, when one hard disk fails, you still have a copy in the second hard disk. Like in RAID 0 above, it can be created with different hard disk sizes but is limited to the size of the smallest hard disk.
So which one should you pick?
For most local SMEs, we would recommend going with RAID 1… unless you’re hosting online games :). Data reliability is more important in most situations and despite the new technologies, hard disks do fail sometimes. Although you may have a weekly or even daily backup arrangement with your hosting provider, RAID 1 adds another layer of the most “up-to-date backup” to give you complete peace of mind.
If you want the best of both worlds, you can always implement RAID 10 (also known as RAID 1+0) – which as the name suggests, combines both mirroring and stripping. In this configuration, you require a minimum of 4 hard disks.
RAID for Dedicated Servers in Malaysia
Note that not every web hosting provider in Malaysia offer RAID with their dedicated server – especially pre-configured, bargain servers. This was what I experienced when I called webserver.com.my for example – the sales person I spoke to said they do not offer RAID at all.
To learn more about RAID, read Wikipedia’s page on Standard RAID Levels.
(Photo credits: Wikipedia)