The WD6400AAV is almost certainly an older WD Green drive, with variable (and usually somewhat low) RPM - normally 5900 RPM or lower. I’d expect more out of it than ~41 MB/sec, but not a lot more. It’s normally suited for long-term or tier 3 storage.
Scott > On Mar 11, 2015, at 10:26 PM, Paul Davis <[email protected]> wrote: > > The math all looks good. Unfortunately, Robin's test is not indicative of the > correct use case. I suspect most people would be OK with the idea that you > can only handle about 50 tracks on an external USB2 drive. The harder results > to explain come from internal drives. I will definitely get my own mac mini > with a spinner inside running tomorrow and re-run the test there with your > additional line, and then redo the math you just did above. We know by > existence proof (aka Logic) that the system can handle 128 or more tracks. > > On Wed, Mar 11, 2015 at 10:08 PM, Hamilton Feltman <[email protected] > <mailto:[email protected]>> wrote: > > > On Mar 11, 2015, at 6:53 PM, Paul Davis <[email protected] > > <mailto:[email protected]>> wrote: > > > > robin reports back that your dd-tester gives: > > > > 41.1806 MB/sec write > > 42.6064 MB/sec read > > > > (Western Digital 6400AAV - we can't find specs online) > > > > He also tried it formatted as FAT32, with essentially no change in the > > results. > > > > Ok, this is enough information to calculate if your drive is performing > within spec. Looking at the first example (block size 65536) > > From your test: > $ ./run-readtest.sh -f 10 -d /Volumes/OSXext/disktest/ 65536 131072 4096000 > # Building files for test... > # Blocksize 65536 > # Min: 8.9910 MB/sec Avg: 9.4645 MB/sec || Max: 0.890 sec > # Max Track count: 51 @ 48000SPS > # Sus Track count: 49 @ 48000SPS > 65536 8.9910 9.4645 0.8898 0.00912 > > So: > file size: 10485760 > num files: 128 > total bytes: 1342177280 > seeks = 1342177280 / 65536 > seeks: 20480 > total_time: 270.484 > > Drive reports: > 42.6064 MB/sec read (44676048 bytes/sec) > Time required to stream 1342177280 bytes -> 30.04 seconds > > Blocksize 65536 > Number of seeks 20480 > Time taken: 270.484 seconds > Time available for seeks: 270.484 - 30.04 = 240.444 seconds > 240.444 / 20480 -> 11.74 ms seek time > > Out of 270 seconds it took to read the 1.25GB, the drive had to spend 240 > seconds performing 20480 seeks, with an average seek time of 11.74 > milliseconds. > This drive seems to be performing well. > > Regards, > Hamilton > > > _______________________________________________ > Do not post admin requests to the list. They will be ignored. > Coreaudio-api mailing list ([email protected]) > Help/Unsubscribe/Update your Subscription: > https://lists.apple.com/mailman/options/coreaudio-api/scott%40stillwellaudio.com > > This email sent to [email protected]
smime.p7s
Description: S/MIME cryptographic signature
_______________________________________________ Do not post admin requests to the list. They will be ignored. Coreaudio-api mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/coreaudio-api/archive%40mail-archive.com This email sent to [email protected]
