Drobo

5400 versus 7200

I know that there are latency issues with 5400 versus 7200 drives – but when connecting to a Drobo (v1/USB)->DroboShare-> gigE network-> PC does that latency make any real difference?

The 5400 ‘green’ drives are quite a bit cheaper – does it make sense to hold out for better performance, or does it not even matter in the long run?

Definitely should go for 7200RPM or the latest 10K RPM Seagate Constellation series drives except w/ limited capacity (max 300GB). I also noticed WD starts making ES (Enterprise series) drives w/ 64MB cache. The additional RPM does make a noticeable impact in both Read/Write operations.

I think that 7200 RPM drive for drobo is overkill.

Considering drobo’s read/write performance I think that there is no need to have disks with more than 5400 RPM. Today’s HDD drives provide enough sustained data transfer speeds, that exceed USB 2.0/FW800 bandwidth.

Besides 5400 RPM drives usually are quieter and cooler - that means that overall noise level from drobo will go down, because drobo will have less job for cooling. If only one drive in your drobo is hot than drobo must turn on it’s fan to cool it down - that’s not good.

So I use 5400 RPM drives and my drobo is connected via USB 2.0. Data transfer speeds are USB 2.0 theoretical maximum (~57 MiB/s) at first, but sustained data transfer speed is ~24MiB/s.

I don’t think that 7200 RPM drives will help you get more.

Well, the 5400 rpm drives are just as fast, theoretically, on the transfer speeds (3.0 GB/s) – the 5400 versus 7200 is more of a latency issue, which is what I am more concerned about.

No, 5400RPM drives are NOT as fast as 7200RPM drives.

Don’t mix interface (SATA II, 3.0Gbps) speed with actual drive performance.

3.0Gbps are achievable only for a very small time as long data is already preloaded in drives buffer.
(For example WD Green 1TB drive read performance is ~77MiB/s)

And regarding latency … again - drobo itself will be the bottleneck.
Anyway - latency would be important if you used this drive as a system drive that needs to serve many small files or in multi-user environment with many requests.

http://www.wdc.com/en/library/eide/2579-001043.pdf
“7200 RPM drives boost data transfer rates 33 percent over 5400 RPM hard drives, providing quicker access to data stored on the hard drive.” says WD & I’m sure Seagate, Hitachi & Samsung have similar publications.
Btw, we are talking sustain, random or mixed transfer & also the 7200RPM drives don’t drain that much power or current!
My vote still goes to the 7200 or faster SATA-II!

First, the Drobo uses BeyondRaid. Second, the Drobo uses USB 2.0 or FireWire 400/800.

A RAID volume may give you a better read performance than a single hard disk. But if you use USB or FW400, than the bottleneck will be this connection. On a FW800 connection there might be a better perfomance.

But think about what you want to do with your Drobo. I used it as a kind of backup media. And I would buy 5400 rpm drives instead of my 7200, because of temperature and noise.

Regards, Nils.

I have both. I use four WD 1TB “Black” drives in combination with a hardware RAID card in my Mac Pro, to get the fastest possible I/O performance (>270 MB/S) and minimum latency.

On my various Drobo’s however, I elected to go with the cooler, cheaper “Green” versions – 24 of them, at last count, ranging from 500GB to 2TB.

Since the Drobos are being used for backup, and not primary storage, reliability and cost are more important than the last tiny increment of performance.

However, if someone has a comparable set of both, it would be interesting to see the performance differences.

This is what I get from my drobo on USB.
Seagate 750GB + Samsung 1TB F2 + 2 x WD Caviar GP 1TB

I say buy 5400 drives because the bottleneck is the slow speed of the Drobo.

I have 2TB+2TB+1TB+1TB in the drobo and get about 20MB/sec.

Just one of those 1TB drives in another enclosure gets about 50MB/sec.

You’d think that with four drives you could stripe tracks and have a boatload of data under the heads without moving the actuators (no seek time), but somehow it just doesn’t work out that way.

@ozymandias, I think everyone missed one key word in your setup - DroboShare. Once you are hooked up to one of those, you could have 72,000 RPM drives with 30Gbps SATA connections, and it would not improve your performance one iota over 5400RPM SATAII drives. If you are sticking with DroboShare, buy the Green drives, save a few watts, and stop worrying.

Even if you don’t stick with the DroboShare, as the others say you probably will not see any difference, so get the Greens and pocket the difference in price and power consumed.

I have three Hitachi drives in my Drobo V1 and they run very hot (uncomfortable to touch when they are working hard). I’m worried that their life is being shortened by their operating temperature. I have one Green drive in there which is just slightly warm. This is probably also a consideration, especially in a V1 which has inferior cooling to the V2. Another reason to get the Greens.

I look at it like this… Sure, the drobo may be a bottleneck with 7200 RPM drives, but the big selling point about the drobo is the ease of swapping drives and once you swap a drive, do you want a 5400 RPM drive?

With the drobo, you will not see any difference between 5400 vs 7200.

Hiya, I just got my Drobo last week for primary storage needs and after a little research on power, performance and accoustics I settled on Seagate Barracuda LP drives which are interesting as they had 32MB cache and rotate at 5900 RPM. All seems great so far :smiley: