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Why are my internal transfer rates so slow?

Last response: in Storage
September 19, 2010 12:09:15 AM

I am hoping you can help me out here. I am getting horrible internal transfer rates and I don't know why. Here is my rig;

i7-870 overclocked to 4.0Ghz
4 GB G.Skill 1600Mhz RAM
128 GB Corsair SSD + Western Digital Caviar Black + Velociraptor
Gigabyte GA-P55-USB3
XFX 9600 GT
Win 7 64bit (PC1) and 32bit (PC 2)

My transfer rates average about 10-20 MB/s, even transfering between a Black and a SSD. The transfer begin faster however (maybe 90 MB/s tops), but they immediately begin to drop to a creeping 12 MB/s within a minute or so. How is this possible?

I have been reading people easily getting sustained transfer rates of 100-125 MB/s on WD Blacks alone. So why are mine so slow? Is is perhaps my motherboard?

Any tips would greatly be appreciated!

September 19, 2010 7:12:20 AM

You had better to download CrystalDiskMark and post a screenshot of a benchmark on your disk .You can get some feedback. Try to avoid reading throughput with partial random reads; which has much lower performance.
a c 415 G Storage
September 19, 2010 4:38:19 PM

Are you really, really sure you're transferring between two separate drives? If you have more than one partition on a single physical drive then it appears as two separate "drive letters" in Windows Explorer - but coping files between them is really moving files from one place to another on the same physical disk. On an HDD this will result in a LOT of head movement and very slow transfers.

If that's not the issue, then use Task Manager (Ctrl+Shift+Esc) to see if you CPU is very busy during the transfer - if so your system may have gotten itself into PIO mode somehow.
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September 20, 2010 8:28:26 AM

I am not sure how to post a screenshot of CrystalDiskMark, but my numbers are as follows;


Sequential Read : 213.864 MB/s
Sequential Write : 96.456 MB/s
Random Read 512KB : 171.387 MB/s
Random Write 512KB : 21.887 MB/s
Random Read 4KB (QD=1) : 21.867 MB/s [ 5338.6 IOPS]
Random Write 4KB (QD=1) : 2.449 MB/s [ 597.8 IOPS]
Random Read 4KB (QD=32) : 17.186 MB/s [ 4195.7 IOPS]
Random Write 4KB (QD=32) : 2.395 MB/s [ 584.7 IOPS]

Test : 1000 MB [C: 25.4% (30.3/119.2 GB)] (x5)
Date : 2010/09/20 4:27:39
OS : Windows 7 Home Premium Edition [6.1 Build 7600] (x64)

Interestingly enough, most of the processing work I go with is with thousands of small files, which seems to be the weakest part of the SSD.

Best solution

a c 351 G Storage
September 20, 2010 2:15:47 PM

Which model is your corsair SSD and have you googled the performance for that model to compare your results to?

The performance of the 4K random read/writes is the one I pay most attention to. There are some SSDs that are really low on random 4K writes(ie some of the Kinston models). In your case "thousands of small files" the 4 K random read/writes would have a large impact (HDDs generaly at the 1 MB/S). Also is your coping, just that, or it it a move. If it is a "Move" you are not only coping, but at the same time deleting which will be slower than just doing a copy.

Are all your HDs set to AHCI Mode - Normally the best mode for SSDs.
a c 415 G Storage
September 20, 2010 3:06:21 PM

rising_suns said:
Interestingly enough, most of the processing work I go with is with thousands of small files, which seems to be the weakest part of the SSD.
...until you compare the SSD with a hard drive. You'll find that the SSD has sequential I/O rates that are around twice as fast as a hard drive, but random I/O rates that are at least 10 times faster.
a c 351 G Storage
September 20, 2010 4:30:54 PM

sminal - While what you said is true: However, a few SSD are only about 2X HDD performance when it comes to 4 K random writes.
IE Kingston SSD
His also indicates a very low 4K random write compared to the norm.
Since he is coping to/from two drives, one must be a HDD. Under the best condition, His 4 K random would be based on 4K random reads Of a HDD plus the time for random writes to His (rather slow) SSD.
September 20, 2010 5:10:55 PM

Wow, you are right. I googled the performance of the Corsair P128 for small file size (4K), and it is surprisingly very slow compared to Intel/OCZ drives (though still faster than my HDD's).

Here is one comparison that blew me away;
Notice the 4K random speed of the Corsair vs. the OCZ! (!!)

From what you're saying then, it seems as though I need to switch from this Corsair to an Intel or OCZ SSD if I want to exploit the full benefits of SSD in the small-file size range?

September 20, 2010 7:20:26 PM

Retired Chief,
Thank you for the link. I noticed that the G.Skill drive in the link has a 50,000 IOPS random 4K write, whereas the Vertex 2 that I am looking at has only an 18,000 IOPS random 4K write. (Not sure if this is significant?).

Also, both the G.Skill and OCZ use the Sandforce controller, correct? If they both use the same controller, then one would expect similar performance from them both?

Sorry for so many questions. This is all new to me!
a c 415 G Storage
September 20, 2010 7:38:29 PM

RetiredChief said:
sminal - While what you said is true: However, a few SSD are only about 2X HDD performance when it comes to 4 K random writes. IE Kingston SSD
That's pretty sad. I haven't paid all that much attention to the "value" drives, and I can see now that I haven't been missing anything...

@rising_suns > if you're really transferring lots of small files then that's doubtless what's causing the problem. People who are getting 100MB/sec or more are transferring a few very large files, not a lot of little ones.

Hard drives aren't significantly better. For example a Velociraptor, widely regarded as having about the fastest access times among consumer hard drives, still only manages about 3.5MB/sec doing small random I/Os:

If you're transferring files TO a hard drive, then depending on how many files you're transferring and how often you have to wait around for them you might find a RAM upgrade to be useful. Windows 7 is pretty good about caching file writes to RAM, and if the quantity of files you're transferring fits into RAM then you'd see those 90MB/sec rates all the way through your transfer. The actual writes to the drive wouldn't complete until later, but with more writes queued up the drive might be able to manage a little better transfer rate as it performs seek optimization.
a c 351 G Storage
September 20, 2010 8:53:11 PM

It maybe a firmware issue, not sure. One articale refers to having a updated SF1500 while anther review indicats SF1200. Mine just arrived an hour ago. - Will not get to check it out untill tommarrow as I have to go bowling.

Here one review

Here is on for the earlier Non-Pro series.

Could not wait, Got Home from Bowling, Whated a TV show. The swapped my Intel G2 out, stuck the G-skill in and using the Image I create using Win 7 BU did a rstore. Rebooted then from Disk manager expaned the volume to fill the whole disk.
September 27, 2010 5:12:58 AM

Well I bought a lot of Vertex 2's, and I am not disappointed. My transfer rates now are way up (interesting much faster on the generic Microsoft AHCI driver than the Intel RST AHCI driver). Here are my numbers now;

Sequential Read : 213.864 MB/s
Sequential Write : 141.776 MB/s
Random Read 512KB : 205.808 MB/s
Random Write 512KB : 141.583 MB/s
Random Read 4KB (QD=1) : 21.507 MB/s [ 5250.7 IOPS]
Random Write 4KB (QD=1) : 73.108 MB/s [ 17848.7 IOPS]
Random Read 4KB (QD=32) : 129.759 MB/s [ 31679.5 IOPS]
Random Write 4KB (QD=32) : 131.866 MB/s [ 32193.8 IOPS]
a c 351 G Storage
September 27, 2010 2:20:44 PM

Great, enjoy. Hope I helped.
October 4, 2010 12:08:05 AM

Best answer selected by rising_suns.
September 18, 2012 3:58:39 PM

rising_suns said:
Best answer selected by rising_suns.

nDose this mean you should Zip a group of small file before transferring them ?