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WD5001AALS-00E3A0 - possibly 2x 500GB platters shortstroked?

Last response: in Storage
September 6, 2010 8:35:54 PM


I have the above Western Digital Black 500GB drive (WD5001AALS-00E3A0) build date August 2010.

When i first got it, i thought it felt a little heavy for a single platter disk, but didn't think much of it. I used 's collection of Western Digital platter sizes to see it reportedly has 1 platter/2 heads.

However, my benchmark read/write from HDtune shows maximum read/writes as 129MB/sec and minimum as 97MB. (here is the read. the write is pretty much a mirror image:

The graph simply doesnt look like a typical HDtune for a single platter disk from my experience. in fact it looks like half - without the tapering off on the end when it reaches the 500gb mark.

Does this looks like the drive most likely has 2 500GB platters, which are shortstroked to make 500GB in total?


Best solution

a c 289 G Storage
September 23, 2010 5:16:35 AM

That's a very interesting observation. Out of curiosity I have gathered a few HD Tune results (see below).

AISI, your drive's maximum transfer rate of ~130 MB/s is consistent with a 500GB platter density. The number of zones also appears halved, suggesting that the drive has indeed been shortstroked.

Other WD5001AALS models appear to have 2 platters with densities of 250GB per platter. My understanding is that the data transfer rate increases with the square root of the platter density.

Hence ...

data rate (00L3B2) / data rate (00E3A0) = sqrt (250GB / 500GB)

ie data rate (00L3B2) = 130 x sqrt (0.5) = 92 MB/s

This is consistent with the benchmark results.

The only question I have is, if the drive is shortstroked, why isn't the seek time much lower for the 00E3A0 versions?

HD Tune read benchmark graphs:

WD5001AALS-00E3A0 - 129MB/s max, 97 MB/s min, 11.0ms access, 8 or 9 zones:

WD5001AALS-00E3A0 - 136MB/s max, 99 MB/s min, 12.1ms access, 9 zones:

WD5001AALS-00L3B2 - 92MB/s max, 44 MB/s min, 12.2ms access, 19 zones:

WD5001AALS-00L3B2 - 92MB/s max, 44 MB/s min, 12.3ms access, 19 zones:

WD5001AALS-00L3B - 97MB/s max, 44 MB/s min, 12.5ms access:

WD5001AALS-00L3B - 92MB/s max, 45 MB/s min (est), 12.6ms access, 18 or 19 zones:

October 3, 2010 4:24:38 AM

Best answer selected by oz-dingo.