Am_Fear_Liath_Mor,

Note while in theory you should be correct about the possible MTBF advantage of SSDs, I've seen a disproportionate number have early mortality issues. And this is with Intel drives. Who knows what you get with the off-brands. Also note another little gotcha with the Intel drives. They are re-seller only, so you can't RMA them directly to Intel -- you have to go through whomever you purchased them from. PITA.

Originally Posted By: Mark_M
Some quick hints:
[*]RAID-1 reduces performance by requiring two operations for every write, but can slightly improve read performance. Using a hardware RAID controller with on-board memory can offset this performance loss.


Sorry Mark, don't mean to pick on you, but this raises an issue I want to point out:

RAID-1 need not perform any worse than a single drive. Drives can be synchronized and write to both drives concurrently.

Which leads me to my point. RAID implementations vary HIGHLY with each implementation. Some are pretty good, most medium poor, and some downright horrible.

Quote:

[*]In my experience, systems with software RAID are more likely to experience failures than systems with no RAID. I'm not sure why this is, but I believe it has something to do with bad software drivers and timing issues.


I haven't observed this, however this does remind me that there is another interesting characteristic people forget about when using RAID:

If you are using a hardware RAID solution, if that controller goes bad, you need to replace it with the same model if you intend to keep using your disks. This can be a factor if you want to run out to a store and pick a replacement so you can get back online that evening.

Software RAID, does tie you to the OS, but you can go get whatever random controller or hard drive that happens to be available.

On the other hand, I don't think too highly of Window's software RAID. *shrug* Tradeoffs.

Quote:

[*]SAS (Serial-attached-SCSI) drives will provide much better performance than IDE, but again, are expensive.


Keep in mind that SATA transfer speeds outstrip the data rate a typical hard drive can supply. Since SATA, unlike PATA uses one controller per drive, typically there is no *performance* advantage over SAS.

Quote:

[*]Avoid drives slower than 7500 RPM. Stick with 10K or 15K drives if you can afford them.


FWIW, you typically pay a significant premium for 10K/15K drives, which can typically be made up by using multiples of the 7.5K RPM disks. And usually more spindles is better.

When purchasing hard drives, note warranty length, and if the drive is intended for constant use (enterprise drives) -- it seems to be a trend drive mfgs now assume you will NOT use your HDD 7x24. Also, try to pick drives that support NCQ (native command queuing).

That said, drives are pretty hit or miss in terms of reliability these days. There is just too much consumer pressure to provide a $100 7.5K RPM 1TB HDD.

We get what we pay for, I guess.

-john


Edited by JohnN (12/27/09 06:52 AM)