Hello all, I’m new here. I’ve got two of these drives in my rig, both bought at the same time. One is running Windows 7 and formatted with NTFS, the other is running Xubuntu and is formatted with ext4. I have benchmarked both drives in Windows with HDTune, and in linux with DIsk Utility, and gotten very similar results with both programs.
The problem is that one drive (the one with linux on it) benchmarks significantly slower, both in data transfer and in access time. I have checked the s.m.a.r.t. attributes on both drives, everything is good. Then I ran a scan for bad sectors and came up with zero. I also notice that the graphs for data transfer for the two drives are completely different, the fast drive drops very little toward the end, while the other one drops quite a bit. The DCM number of the fast drive is EBNNHTJCH, and the DCM of the slow one is DHNNHVJCH…I know this means there are some differences, but what would they be? Is there maybe a different number of heads or platters? Even if that is the case, the 15.2ms access time seems horrid. I’ve got a 5.5 year old Samsung SP2504C in this same rig, formatted with ext4, and its access time is 14.3, though its data transfer rate is significantly slower than the slower WD drive.
Could there be something physically wrong with the drive? I’m OK with it being a little slower, that isn’t a huge deal, but I do want to know if its possibly a future problem child?
If the format type is the only difference between the two hard drives. Why not format the slow hard drive in NTFS and check if that can affect the performance with the benchmark program that you are using?
Alucardx23…I took your advise and formatted the drive with NTFS and ran the HD Tune test. My results were exactly the same as when it was ext4, except for access time, which jumped to 15.7! I also tried a different cable, and it made no difference. I’m really thinking there is a difference in the physical construction of the drives, due to the different DCM numbers, but could this really make such a huge difference?
Mmmm that is weird. If both of them have the same model number they should not have a big difference in performance. The DCM number should not affect the performance so much. What is the difference that you get with the transfer rate between the two HDD?
Its a 15.6 MB/s average difference between the two and a 2.2ms access time difference. Also, oddly enough, the faster drive when benchmarked in linux shows even faster max transfer rate than in HD Tune, something along the lines of 125 MB/s. Someone on another forum mentioned that the graph for the fast drive is oddly very flat, and I agree with that, it doesn’t slow down as much toward the end of the drive as you would expect.
I’m really kind of stumped by this, I’ve checked everything imaginable, from BIOS settings, to cables, to different filesystems and benchmark software, and always roughly the same exact results. Like I say what concerns me the most though is the slow access time, could something be off about the read head assembly in the drive? Ive looked into disabling any kind of acoustic management through Crystalmark, the options to do so are greyed out on both my WDC drives. I appreciate the help so far though, eventually we’ll get this figured out!
AISI, the “slow” WD drive and the Samsung drive both show the typical 2:1 ratio between the transfer rates at the outermost and innermost zones. This is to be expected since the diameter (and circumference) of the outer and inner tracks is in the same ratio. That is, the innermost zone has half as many bits per track as the outermost zone, and therefore half as many bytes pass under the head during each revolution. The WD graph also shows 16 or so steps corresponding to each zone.
If you now compare the “fast” WD graph against the slow one, it appears that there may be only two or three zones. In fact the transfer rate at the 100% mark on the fast graph corresponds to the 35% mark on the slow graph. This suggests that the fast drive has been shortstroked, and that its full-stroke capacity is more like 914GB (= 320GB/0.35). Therefore I suspect that the fast 320GB drive is actually a 1TB drive that has had its capacity truncated. Shortstroking would also explain why its access time is significantly better.
Another clue as to what may be going on is the DCM (Drive Configuration Matrix). The following thread would suggest that there is a difference in the head stacks of the two WD drives: http://forum.hddguru.com/western-digital-what-dcm-t6488.html
I would think that the 1TB drive would have 3 platters and 6 heads, whereas the 320GB drive would have 1 platter and 2 heads.
One final observation I’d like to make is that the maximum sustained transfer rate (105 MB/s) is a lot less than what is touted in the datasheet (126 MB/s).
