fzabkar wrote:
The second "3" in the model number indicates that the drive has 32MB cache.
Yes. The data sheet for the drive indicates it should have 32 MB cache.
fzabkar wrote:
I believe Seagate's SeaTools may be able to detect the cache size using vendor specific ATA commands.
I ran SeaTools v2.22 (GUI) for DOS and the "short test" said the drive was "OK." There was no option to get further information. From the SeaTools for Windows User Guide (URL below) it looks like there is a "Drive Information" option in that program that likely will query the drive with vendor specific ATA commands.
http://www.seagate.com/staticfiles/support/seatools/user%20guides/SeaTools_for_Windows.EN.pdfUnfortunately when I boot Windows the ST31500341AS can only be accessed through an add-in PCI HBA card because my mobo has no native SATA ports. I'm currently not employed and will not be buying a new mobo in the next month or two. SeaTools for Windows cannot see the ST31500341AS when it is connected to that particular PCI HBA. With the appropriate drivers installed Windows sees the drive just fine.
fzabkar wrote:
AIUI, the transfer rate out of cache should be approaching the interface speed, ie 300MB/s. In fact the drive's maximum sustained data rate off the platters is 130 MB/s, so the data rate into and out of cache must be much faster than that. ISTM that your system must have a bottleneck somewhere.
The bottleneck is, of course, the PCI HBA card.
fzabkar wrote:
As for HD Tune Pro's cache test, could you show us the graph?
I connect my SATA boot drive to a PATA connector on the mobo via a SYBA SD-ADA50016 IDE <-> SATA bi-directional adapter that uses the Sunplus SPIF223 chipset. As far as I'm concerned it works just fine. Yes, it's a bit slow. Some folks on this board will likely laugh at it ... no big deal.
I unplugged the boot drive and plugged in the ST31500341AS to the SD-ADA50016. I then booted from a BartPE ISO CD and after that installed HD Tune Pro v4.60 which complained about the lack of a dll which I then copied into the same dir as HD Tune. After that it ran the cache test fine.
I hooked things up like this to (maybe) get a little more speed on the cache test and to check the results of the first test.
This time the speed of the transfers coming out of the cache were about 70 MB/sec. The prior test on the PCI card HBA had gotten around 60 MB/sec. The screen capture from the second test is below. The first test also had a 15-20% speed dip between 2-4 MB ... similar to this test. I realize I don't need to have the "4KB align" option selected, but it shouldn't hurt.
Attachment:
File comment: 64 MB cache?
HDTP_64MB_cache_QQQ.png [ 18.25 KiB | Viewed 9422 times ]
As far as I can see the main result of the test is that the speed remains relatively constant even though the data transfer size increases beyond 32 MB. That says to me that the drive has more than 32 MB of cache. I suspect that a situation exists similar to the "cache swap" in the article at the URL below. That HDD was supposed to have 8 MB of cache, but on tear down was observed to have 32 MB cache. I've also heard of situations where folks were supposed to get 8 MB cache and instead got 2 MB cache.
http://www.storagereview.com/western_digital_scorpio_blue_review_750gb_wd7500bpvtfzabkar wrote:
... remove the PCB from the drive and record the markings on the SDRAM chip. Then refer to its datasheet.
The drive is brand spanking new and under warranty. Maybe in a few years I'll peek at the "chip side" of the controller PCB, but not now.
I thank you for your time and your suggestions fzabkar.
Cheers, mate!