How important are hard drive specs like RPM and cache size?

Petros_K · Feb 23, 2014

Here's my dilemma: I got a computer from a refurbisher that had a faulty hard drive in it. This is a 250 GB Seagate Barracuda ES.2 model ST3250310NS with a spindle speed of 7200 RPM and a cache size of 32 MB. They sent me a replacement for it that's 500 GB of storage, but it's a Seagate Pipeline HD ST3500312CS that has a spindle speed of 5900 RPM and a cache size of only 8 MB. I didn't need the additional storage, but should I be concerned about the potential for downgraded performance?

I see from the Seagate website that the Pipeline series hard drives are intended for things like security systems and DVR storage (in 24/7 applications like streaming media). I'm not saying these drives can't both run an operating system like Windows 7, but compared to the Barracuda the Pipeline hard drive could lead to slower performance when running certain applications such as video editing, photo editing, and digital recording, yes?

rehed21 · Feb 23, 2014

The 5900 rpm drive will be slower than the 7200 rpm drive and would not be good for an OS or program drive (OK for storage though). The refurbisher should have sent you an equivalent or better hard drive, not a larger one.

aldan · Feb 23, 2014

he is right,send it back.that drive is an oddball from the get go.nowadays most drives are 7200rpm unless it is a laptop.some drives go as high as 10,000rpm.laptop drives were usually 5400 rpm,so this one seems to me to be a special use drive.the drive they sent you is garbage and if this is a warranty situation,tell them you want an equivalent drive to the one that was in there.

fzabkar · Feb 23, 2014

The ST3250310NS and ST3500312CS both have 2 heads. This suggests that the Pipeline drive has the newer technology.

All other things being equal, the 500GB drive should have a transfer rate that is 1.414 (= sqrt 2) times as fast as the 250GB drive. However, a 5900 RPM drive would be slower by a factor of 0.819 (= 5900 / 7200).

Combining the two factors ...

(transfer rate of ST3500312CS) / (transfer rate of ST3250310NS) = sqrt(2) x (5900 / 7200) = 1.16

This would suggest that the Pipeline drive should be faster by 16%. I would consult the Product Manuals, though.

Barracuda ES.2 Serial ATA Product Manual:
http://www.seagate.com/staticfiles/support/disc/manuals/NL35%20Series%20&%20BC%20ES%20Series/Barracuda%20ES.2%20Series/100468393h.pdf

Pipeline HD.2 Series SATA Product Manual:
http://www.seagate.com/staticfiles/support/disc/manuals/ce/Pipeline%20HD%20Series/100529372a.pdf

Alternatively you could search for HD Tune test results.

http://images.google.com/images?q=ST3250310NS+%22hd+tune%22&sourceid=opera&tbs=isz:m,itp

hoto&tbm=isch
http://images.google.com/images?q=ST3500312CS+%22hd+tune%22&sourceid=opera&tbs=isz:m,itp

hoto&tbm=isch

As for the cache size, I don't think this has any significant impact on performance.

Petros_K · Feb 23, 2014

fzabkar :

Thanks for responding here. That's impressive math, but I'm not sure it's relevant when you check the actual specs:

The Pipeline and the Barracuda both have 2 heads and 1 disk each.

The specs that lead me to believe that the Pipeline HD.2 will ultimately be slower:

Spindle Speed: 5900 RPM
average seek time, read: 14msec
Sustained data transfer rate: 120 Mbytes/sec. max
cache buffer: 8 Mbytes

Compared to the Barracuda ES.2:

Spindle Speed: 7200 RPM
average seek time, read: 8.5msec
Sustained data transfer rate: 105 Mbytes/sec max
cache buffer: 32 Mbytes

I thought not only for OS files but for applications that are more hard drive intensive like video editing, photo editing, and digital recording that a higher spindle speed and larger cache buffer was desirable. That's not true in this case and the Pipeline will still be faster?

If you go to the Seagate website, you can see the Pipeline hard drive is intended for security and DVR storage applications (which might explain the low 8 MB cache).

Petros_K · Feb 23, 2014

fzabkar :

Someone had this to say about the importance of hard drive cache size (as it pertains to programs for digital recording in this particular case):

"A larger buffer{cache memory} is essentially a fast buffer between the drive platters and the computer. It is faster than physically accessing data from the drive platters when reading or writing. Complex algorithms determine the practical use of cache memory.

As specific data is requested from the hard drive, the drive logic may anticipate that more accesses will ask for the same data. To increase performance and to avoid having to keep reading the same data from the drive several times, the data is put into the cache memory, so that the drive will be able to handle future requests immediately. Often, additional data that is usually requested afterwards is cached as well.

Reading data from the cache memory is much faster than reading directly from the drive platters themselves. The more data that is cached, the better the chance for cache access over physical platter access. Thus, as drive cache size increases, so does overall drive performance." http://homerecording.com/bbs/general-discussions/digital-recording-computers/24-bit-recording-82798/

Not true?

GhislainG · Feb 23, 2014

rehed21 :

Why wouldn't a drive designed for 24x7 operation not be good as an OS drive? If the ES.2 was several years old (they were released in 2007), then the OP should consider keeping the ST3500312CS drive if it's brand new (check the warranty expiration date on Seagate's site). Performance wise the new 5900 RPM drive probably is faster.

Petros_K · Feb 23, 2014

GhislainG :

The 24/7 "always on" capability of the Seagate Pipeline is kind of a moot point here. Comparing two SATA hard drives, spindle speed, cache buffer size, data transfer rate, seek time, and the number of platters and heads, are what's supposed to matter when comparing two drives to estimate which one will be faster (unless I got it wrong).

fzabkar · Feb 23, 2014

Cache size would be important for "bursty" data, but would be irrelevant for streaming data. Seek time would also be relatively unimportant for the latter, but would be important if you had lots of small files or if the file system were highly fragmented.

The idea behind caching is so that the OS can send data to the drive without waiting for it to complete the write operation. For example, if the cache size were 8MB, and if your bursty data consisted of files smaller than 8MB, then the OS could send the data to the drive at a rate limited only by the SATA link speed and the performance of the drive's SDRAM and MCU. Larger files would fill the cache and cause the OS to wait for the cache to be emptied.

GhislainG · Feb 23, 2014

Petros_K :

Because of its higher platter density, the 5900 will win when reading large files and loading applications (faster transfer rate) and it may lose when reading small or random files. A user probably won't be able to notice the difference between these drives.

Petros_K · Feb 23, 2014

fzabkar :

So then you disagree with this quote from above: "Reading data from the cache memory is much faster than reading directly from the drive platters themselves. The more data that is cached, the better the chance for cache access over physical platter access. Thus, as drive cache size increases, so does overall drive performance."

And you still think despite the slower spindle speed of the Pipeline HD.2 hard drive it will:

a) generally be faster than the Barracuda ES.2
b) will not negatively impact the loading of OS files or slow it down
c) will have marginal negative effect on applications that are hard drive intensive (e.g., video and sound editing)
d) and if not better is certainly an acceptable replacement for the Barracuda ES.2

(Note too, in ref to the other thread I posted, the Pipeline hard drive they sent me is a retail version, not an OEM part like the Barracuda)

Petros_K · Feb 23, 2014

GhislainG :

I was misunderstanding the data transfer rates and didn't realize the Pipeline can actually do 15 Mbytes more per second. Thanks for clearing that up.

--Could you just clarify what you mean by "higher platter density?" Do you mean because the disk in the Pipeline is essentially the same size as the disk in the Barracuda, and they each have only 1 disk, the data on the Pipeline is more densely packed together making it slightly easier to access?

--Note here too that digital recording programs and even video editing often require running a lot of files at the same time, so in these cases the Barracuda hard drive (7200 RPM) will outperform the Pipeline (5900 RPM) ?

GhislainG · Feb 23, 2014

A larger cache helps very little. You'll rarely write or read a file that fits completely in the disk's cache; enabing write cache in Windows helps a lot more.

a) yes
b) it will be faster because of the higher transfer rate
c) it will be better because they are large files
d) absolutely.

On the other hand, nothing beats an SSD.

Petros_K · Feb 23, 2014

GhislainG :

LOL I can think of one thing that beats an SSD at the moment: saving hundreds of dollars (at least for now) ! Thanks for your comments.

fzabkar: Do you agree with Ghislain ?

Petros_K · Feb 23, 2014

Just wanted to share this from the PassMark Software website:
http://www.harddrivebenchmark.net/hdd_list.php

Seagate Barracuda ES.2
model: ST3250310NS
Disk Rating (higher is better) 604
Rank (lower is better) 1376

Seagate Pipeline HD.2
model: ST3500312CS
Disk Rating (higher is better) 620
Rank (lower is better) 1332

For what it's worth, these rating seems to be congruent with comments here suggesting the Pipeline is a slightly better hard drive.

GhislainG · Feb 23, 2014

I hope fzabkar agrees with me because I agree with him. The performance difference is minimal, but you lost nothing getting that replacement drive, particularly if it's under warranty.

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