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"Short Stroke" VMAX Disks in the Factory...
Please note the "symdisk list" below:
Note that "Actual" says 279 GB, but "Total" says 139 GB; i.e. - it looks like EMC installed a 300 GB disks and formatted it as a 146 GB disk.
When we pursued this with our EMC reps, they said that the disk had been "Short Stroked" in the factory. This means that when our VMAX was being put together in 2009, they didn't have enough 146 GB 15K FC drives to build our VMAX, so they took some 300 GB 15K FC drives, formatted them as 146 GB, and inserted them in "sleeves" with 146 GB badge emblems on the front; and put them in our machine. We have 39 out of 900+ drives like this.
I'm curious, does anyone else have this? Actual > Total ?
Stuart
StuartA58
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September 12th, 2012 07:00
Thanks for corroborating my question so quickly (I love forums.).
Howerver, I have been told that your speed statement is not true. The transfer rate of a disk is entirely dependent on the rotation speed - i.e. a 146 GB FC 15K rpm disks performs the same as a 300 GB FC 15K rpm disk. The number of tracks doesnt' have any bearing on transfer rate. Isn't that true?
Stuart
RRR
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September 12th, 2012 07:00
The story is correct, but you should be glad, since you paid for 146GB and in fact they perform even better than regular 146GB drives, since only half of the surface is used !
Quincy561
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September 12th, 2012 08:00
Yes, once the head is where it is supposed to be, the rotational latency will be the same.
However the maximum seek time will be lower because the maximum seek distance will be half.
RRR
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September 13th, 2012 05:00
So performance IS better, yes? For random I/O that is.
Quincy561
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September 13th, 2012 06:00
Yes, the disk response time will be better.