Tell me more ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.

I know there are a couple of key characteristics that determine the reliability of HDDs, but is there a difference between 2.5" and 3.5" drives?

In the past I've always assumed that 3.5" drives were likely to be more robust...but I am now questioning that because I have absolutely no evidence (let alone a half-baked theory) to back it up.

share|improve this question
Between which 2.5" and 3.5" drives? A questions such as this cannot be answered without context. – John Gardeniers Mar 8 '11 at 11:41
1  
Let's just say there is no systematic difference that inherently makes 2,5" drives less reliable than 3,5" drives, both can be considered as equal. But of course there is a difference between a 15K RPM SAS 24x7/RAID drive in 2,5" and a cheap desktop drive in 3,5" :) – SvW Mar 8 '11 at 11:49
Closers: How is this an argumentative topic? <Stumped> @Sven: That's the kind of answer I was looking for....why in a comment? Cheers, though! – Stu Thompson Mar 8 '11 at 12:03

3 Answers

up vote 1 down vote accepted

No not really, 2.5 and 3.5 inch drives are mostly the same, including interface and whatnot but 3.5 inch drives are usually faster and larger in space because there is more stuff you can fit into 2.5 vs 3.5 inches. 3.5s are cheaper because of space constrains but usually no more reliable than a 2.5 and vise versa. (in practice)If you could fit a 3.5 drive do it, it'll be cheaper and bigger(storage wise)

share|improve this answer
1  
Bigger and cheaper is not everything when it comes to servers. If you run a large database, you would like to have fast access times and use 15K RPM drives, which are always only 2,5", even when in a 3,5" case (this is because the rotational forces get too strong at the outer edge of a 3,5" platter at 15K RPM). Using 2,5" drives then has the advantage that you can fit more drives into the same space. – SvW Mar 8 '11 at 12:56
I've seen performance numbers on HP ProLiant equipment showing transfer rates on 2.5" 10K's to be as fast as 3.5" 15K's. So "usually faster" should be validated with the HD or server vender. – Bret Fisher Mar 8 '11 at 14:40
I tried to stick to generalizations but you both are right – Jacob Mar 8 '11 at 19:20

You can't base that just on the form-factor. What's way more important is how the vendor dedicates the hard disk. There are consumer disks with both sizes, which are mainly meant for running just a few hours a day and are lightly loaded.

Enterprise disks (SAS, nearline-SATA) are dedicated for 24/7 usage and higher loads. So if you need reliability, use those.

The most important characteristic to consider when choosing between 3.5" and 2.5" is typically size and energy consumption. If you are tight on both, you should choose 2.5", else you could go with 3.5" which are typically cheaper per GB.

share|improve this answer

The real question is what are you you trying to do? If you have a choice between two enclosures, check with the vendor(s) to see what disks are being put in, and see what the warranty period and the manufacturers MTBF on the drives.

Personally, I have seen 2.5" drives fail on me more frequently than 3.5" drives, and I have seen 2.5" drives have 1-3 year warranties versus 3-5 year warranties for 3.5" drives. To be sure, 2.5" drives are more likely to be installed in laptops, which tend to bounce around and have less ventilation.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.