Enterprise or not enterprise?

I'm having a hard time deciding whether to buy enterprise drives or just normal drives. I'm planning to build a server that will run almost all the time.

My question is do I suck it up and shell out for the enterprise drives or will consumer drives do?

Good Question.

There are fundamental differences between drives and their "grades".

A consumer grade drive, will be rated to do a certain amount of GB of data a year or have a listed Mean Time Before Failure (MTBF). These are commonly (well mostly) on the SATA interface.

A enterprise grade drive is basically a drive that is validated to do much, much more than a consumer drive in a year and have a longer MTBF. They are commonly engineered with higher tolerances to allow them to almost certainly achieve their rating. These drives will more commonly be found with the SAS interface, although there are many options with SATA.

Does this mean they are better? Yes and no. Just because it is rated to do more doesn't mean it won't die in a month. It most likely won't but it could. Its a mechanical device and it will fail at some point.

You could buy a consumer drive that is easily a quarter the price of its enterprise counterpart AND replace it three times before you cross the cost of the enterprise drive, by which time the enterprise drive may of failed.

Where these drives greatly differ is their interface. SAS is essentially SATA +1. SATA can do full duplex communication in only one direction at a time. So you get the full read or the full write communication to the drive at a time, not both.
Unlike SAS that can do full duplex in both directions at the same time (as 1 SAS is effectively 2 SATA in wiring). This means SAS drives can, and usually are, way faster than SATA drives. (this is also reflected in their spindle speeds)

The only draw back is that you will need a SAS HBA or RAID card to connect them to. (some enterprise grade mobo's have SAS on board).

So my recommendation, if your only using a handful of drives (say 4 or less) then you may never have a problem with consumer grade drives. If your packing a lot of them close together, consider enterprise grade drives (due to heat and vibrations).
If you need MEGA throughput (or going to be doing lots and lots of random read/writes) then consider moving to SAS drives.

I have 12 consumer grade drives in my NAS, not one has failed with some being 5+ years old. (I usually end up replacing them with greater capacities before they fail). I do have 4 SAS drives in a RAID 5 in my main virtualization server entirely due to the load.

unrecoverable error rate ( https://en.wikipedia.org/wiki/RAID#URE ) is different, higher value for enterprise hdds.

Thanks a ton Zanginator. If I'm doing virtualization would you recommend going ahead with the raid setup with SAS?

For personal use;

There is no point getting enterprise drives unless you are going for 10k+ rpm sas drives. If you need high io performance you should pay the extra.

For regular 7200-5400 speeds the cost saving benefit of consumer drives outweigh the higher mtbf and shinier firmware of enterprise drives.

A disk may fail for whatever reason so having a decent backup system > higher rated drives.

You could get away with using a RAID using SATA drives. I used SAS entirely because I was trying to mitigate some I/O wait issues I was having with a SATA raid. (albeit I had about 40vms running on one 24 core machine).

If your going low volume, then you could use SATA raid. (or even an ssd)