Is there a disadvantage with using 2.5 drives?

[MJLezan]

I am thinking of putting together a small unit running Raid10 using 4x500Gb 2.5 drives for my business backup. The drive I am thinking of using are WD Black 32mb cache.
This might just be very obvious I just don't know, I am just trying to build a small low power system and thought this might be the way to go.
Here are the drives I was thinking of using: http://www.newegg.com/Product/Product.aspx?Item=N82E16822136561

 

[Milhouse]

Cost, mainly, as the 2.5" drives are expensive in comparison with the 3.5" equivalents. Also, their capacity is limited in comparison with 3.5" drives (largest currently available is 1TB whereas 3TB 3.5" drives are available).

As it's a backup server, if you enable power management on the disks so that they spin down quite quickly (ie. after 10 minutes of idle) then the box would be very power efficient in terms of power consumed by the disks.

Personally, I wouldn't bother with 2.5" disks for a dedicated backup server, and would instead go with 3.5" disks with power management/spin down enabled, just as power efficient as 2.5" disks in that case (ok, the 3.5" disks may use a little more juice when active but hardly enough to make a difference unless in use 24/7), and the 3.5" disks will be cheaper with greater potential storage capacity.

 

[matthewowen01]

cost and speed. you're gaining a small footprint at the expense of speed and money. speed shouldn't be too bad though, price is the main disadvantage.

other than that, you're good. i would recommend raidz2 instead of 2 stripped mirrors. you'll get 2 disks of redundancy instead of 1 and as a backup that can be important.

 

[MJLezan]

cost and speed. you're gaining a small footprint at the expense of speed and money. speed shouldn't be too bad though, price is the main disadvantage.

other than that, you're good. i would recommend raidz2 instead of 2 stripped mirrors. you'll get 2 disks of redundancy instead of 1 and as a backup that can be important.

Thxs Milhouse & matthewowen01 for the quick reply's.
Space is not a huge concern but reliability and redundancy is.
This is all new to me so I will checkout the raidz2.

Thxs again

Mike

 

[matthewowen01]

Thxs Milhouse & matthewowen01 for the quick reply's.
Space is not a huge concern but reliability and redundancy is.
This is all new to me so I will checkout the raidz2.

Thxs again

Mike

it's comparable to raid 6, n-2 data drives and 2 drives of parity. this is better for redundancy than a raid 10 as you can always loose 2 drives, with a raid 10 you can always loose one and sometimes loose 2.

 

[jgreco]

The disadvantage to 2.5" drives is that you are paying a lot more per byte, as noted. However, there are significant power savings - some 3.5" drives take 10-15W, while Apple's entire Mac Mini Server at idle, with 2 x 7200RPM drives, takes 12W total.

You can also get drives like the Momentus XT which may be useful in some scenarios, but in all likelihood 2.5" drives are not that practical for a NAS unless you have a shelf of them or something like that, because a bunch of smaller drives can definitely boost your transactions per second, and the smaller form factor magnifies seek speeds.