Sata HDs - 2.5 vs. 3.5 inch

SeanW

I read somewhere that places like data centres were starting to use 2.5 inch hard drives for power-efficiency and other advantages.
In terms of heat generation and energy efficiency, or in any other respect, are there any benefits to using 2.5 inch HDs over 3.5 inch HDs (or the reverse).
This is going to be an questions for me, in about 6 months when I start spec'ing up a new rig.

astrofool

In a desktop machine, go with a 3.5inch drive, they're generally faster, have higher capacities, lower seek times, more on board cache (ssd's aside, where form factor doesn't matter that much).

They are used in enterprise due to being able to use them in high density configurations, especially as a replacement for 3.5inch SCSI drives. In enterprise the speed comes from being able to use multiple drives in a RAID 5 (or higher) configuration, they are lower capacity (max 320GB each usually), but can have very high spindle speeds (15k+) which need far too much cooling to be able to be used in a desktop. In this instance a 15k 2.5 inch drive is more energy efficient than a 3.5 inch 15k drive, but a 7.2k desktop drive will be more efficient (and quieter) than either of them.

SeanW

My next rig will have at least one large SSD, most likely two, for anything speed sensitive such as OS, pagefile, programs, games, documents, nero tempfiles and so on. Traditional HDs will be used only for bulk storage, downloads, music etc, where my objectives will be more about capacity and efficiency, so they can be as slow, or even slower than what I'm using now.
Hence I'm looking for the combo that offers the most space with the least power needs/heat generation.

astrofool

Then you're still far better off with a 3.5 inch drive, better performance and much higher capacity then 2.5 inch drives. A 1.5 or 2TB drive will probably be sufficient.

Chosen

astrofool wrote: »

They are used in enterprise due to being able to use them in high density configurations, especially as a replacement for 3.5inch SCSI drives.

Correct.

astrofool wrote: »

In enterprise the speed comes from being able to use multiple drives in a RAID 5 (or higher) configuration, they are lower capacity (max 320GB each usually), but can have very high spindle speeds (15k+) which need far too much cooling to be able to be used in a desktop.

(kind of) incorrect: The capacity on the 2.5" SAS drives to date, can be 36Gb, 73Gb, 146Gb or 300Gb; the next models will have 450Gb and then 600Gb.
Regardless of the RAID level you are using, the speed increase comes from the fastest rotational speed (15k rpm) combined with the smaller surface of the platters, resulting in 4ms and less access times.

astrofool

Chosen wrote: »

Correct.



(kind of) incorrect: The capacity on the 2.5" SAS drives to date, can be 36Gb, 73Gb, 146Gb or 300Gb; the next models will have 450Gb and then 600Gb.
Regardless of the RAID level you are using, the speed increase comes from the fastest rotational speed (15k rpm) combined with the smaller surface of the platters, resulting in 4ms and less access times.

Yep, I was kind of flitting between enterprise and desktop/laptop 2.5" drives. The 3.5" drives will have a higher throughput on the outer edge, but slightly higher latency, however the extra space they take up is critical in a datacenter (esp. given that capacities are comparable between 2.5" and 3.5" drives at 15k, I think they may be using the same platters now anyway?). You also need a lot of extra cooling for a 15k drive.

SeanW

astrofool wrote: »

Then you're still far better off with a 3.5 inch drive, better performance and much higher capacity then 2.5 inch drives. A 1.5 or 2TB drive will probably be sufficient.

I wouldn't need that much space, not now at least, I was thinking of perhaps a single 500GB drive or a RAID array of 320/400/500GB drives (500 is the common upper limit with 2.5 drives these days). Specifically, because the contents involved will be totally time insensitive, I was wondering if there would be any benefits to using (2.5) drives with 5400RPM platter speeds.

Mac daddy

Any decent enterprise system does not use Sata hard drives we use SAS drives 2.5" drive higher density and 10k and 15k, and yes we have alot of system 5000+ systems and 1800+ Bl460/80 C class blades.

2.5" SATA drives are used in laptops and most ssd hdds are 2.5" in size.

Stick with a 3.5" disk unless you want to go down the ssd route or upgrading your laptops hdd, as for storage if the disks isn't going to be used a aw full lot consider going for the green power western digital drives to save a lil bit on your power bills.

If its a disk that will be used constant as storage look into the samsung F1 disks.

Chosen

Mac daddy wrote: »

If its a disk that will be used constant as storage look into the samsung F1 disks.

Like the one I bought 3 months ago and died about 6 minutes ago?

SeanW

Mac daddy wrote: »

Stick with a 3.5" disk unless you want to go down the ssd route or upgrading your laptops hdd, as for storage if the disks isn't going to be used a aw full lot consider going for the green power western digital drives to save a lil bit on your power bills.

Yeah, I'm considering the "Green Power" disks as well. Like I said, the HDs in my upcoming rig will be for time-insensitive bulk storage only.

Thanks for all the info guys