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I/O density ?
Hi,, buddy: so what is I/O density? it because this section said "For a single disk drive, various disk vendors provide the disk specifications on their Internet product
sites. Since the access times for the Fibre Channel disks (not FATA) are the same, but they have
different capacities, the I/O density is different. 146 GB 15k RPM disk drives can be used for access
densities up 1 I/O/GBps. For 73 GB drives, the access density can be 2 I/O/GBps and for 300 GB
drives, it is 0.5 I/O/GBps. While this discussion is theoretical in approach, it provides a first estimate. It
is important when sizing a storage subsystem; you should not only consider the capacity but also the
number of disk drives needed to satisfy the performance requirements. " ,,, so that means lower capacity has better performance ?
christopher_ime
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February 17th, 2013 14:00
With all else being equal such as mechanics, rated RPM (angular velocity), controller, cache, physical location on the platter (in consideration of linear velocity), etc., when comparing 2 otherwise identical drives, then differences in density can make a difference as more bits can be read as the drive head passes over the platter.
liulei_it
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February 17th, 2013 03:00
The page 16 ,
AnkitMehta
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February 17th, 2013 08:00
Hi lei liu,
We would love to answer your queries with regards to Performance on EMC Products. IMHO, IBM Technical Support or Support forums will be the best group who can answer performance realted questions for IBM DS8000.
Ankit Mehta
EMC Unified Storage Performance Expert/GURU.
liulei_it
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February 17th, 2013 13:00
thank you , for they eaid , the smaller capacity would be better performance ? confuse me.
liulei_it
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February 17th, 2013 16:00
Thanks a lot. The more bits makes better, But for example. We had had 73GB FC disk, 146GB FC disk and 300GB FC disk. then for more bits, we need to choose 73GB FC disk instead of the more capacity ?
liulei_it
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February 17th, 2013 19:00
Thanks ，I seem know it