Hot spare is a handy option, but...

 It is very good to have a hot spare drive, but the hard drive used as a hotspare ought to be tested every now and then.

 Suppose you build your own RAID array and assign N hard drives (including the hot spare disk) to the array. Surprisingly there exists 1/N probability that exactly the disk which is designated to be a hotspare will be the first failed disk. And now you no longer have a hot spare.

 If one of the array member disks fails you find out that the hot spare disk has already failed. To avoid this you need to scan a hot spare on a regular basis or stick to RAID6E or RAID 5E/EE layout.

Before building an array

When building a massive-capacity storage system, take into account the following concerns:

• needed size
• redundancy
• performance
• array cost

Once you have considered points listed in this post it is needed to decide if you need to build your own storage unit or just order ready-made storage. If your choice is the latter option then have a look at this one of RAID Tips. If you decide to build your own storage then review the entire lot on www.raidtips.com.