W dniu 2010-10-13 03:05, Ron Hawkins pisze:
[...]
The difference between the cost of midrange and enterprise storage has
little to do with end-to-end data protection, because it's all SCSI, SAS and
SATA once your write leaves the FICON channel on Enterprise. It has much
more to do with survivability, availability, scalability, and software
options or lack thereof on midrange storage
The best illustration of this were the last set of ratings that the now
defunct RAID Advisory Board issued, where most Enterprise Class controllers
were classified as Disaster Tolerant Disk Subsystems, and midrange was
typically classified as Fault Tolerant Disk Subsystems.
Typically midrange storage will stay connected and keep running if a
component fails, but FRU replacements, upgrades and suchlike are likely to
be disruptive - they're not five nines in all situations and that's why they
are cheaper.
The original question was: Why *THE SAME* dasd box costs less when it's
sold for FBA (distributed) systems, and costs more when it's CKD. Same
hardware, usually comparable set of software features.
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