Fred Schmidt pisze:
The specs certainly read well in comparison to our current IBM DS6800. Call me
a nervous Nellie or what have you, but seeing how nobody else here in Australia
is supposedly using SAS disk for the mainframe, I still have the following
concerns...
- will it support the required number of logical paths for 20 odd LPAR's?
This is an issue of (emulated) Control Unit - USP, not real HDD under
the cover. It has *ABSOLUTELY NOTHING* to do with FC, SATA, PATA, SAS,
SCSI, SSA, whatever interface behind.
- could mainframe performance be degraded significantly by load on the
open systems disk, that would make up the majority of data stored on the
AMS2500?
It depends. It depends on comparison of your current DASD to the new
one, it depends on the workload of your AMS by other systems, it
depends on distribution of dasd chunks assigned to mainframe , etc.
- Can the mainframe DASD part of the storage be isolated from those "whoops, I
formatted the wrong disk" type actions against open systems disk?
IMHO no, but it depends on the tools used for AMS administration.
- Can it do custom volume sizes for DASD?
Nothing changed. Yes. Again: it has ABSOULTELY NOTHING TO the interface
of HDDs.
- Will it work to mirror to a second DR site? Any distance limitations?
Nothing changed. Yes.
- How long does the battery backup for the cache hold the data not yet
destaged to disk for?
Check documentation of AMS and USP. Nothing changed because of SAS
interface.
- After total power failure, how long does it take for the AMS2500 and
USP-VM to become operational again?
I don't know, but it is still unrelated to SAS interface. I would bet
approx. 30 min. (very roughly).
(from another post)
Hmmm... I don't claim to be an expert on this at all, but from my
reading, the architecture of SAS compared to FC-AL disks seems to be
completely different.
What is completely different???
HDD itself is not different, in many case this is the very same drive
model with another interface. In term of interface - since it is
invisible for mainframe it's not relevant. And the interface is quite
similar - the same set of "CCW-like" commands is used in both.
BTW: I don't know what you compared, but FC-AL is rather fading
topology, nowadays the most popular flavor of FC is switched FC, without
loops. It has nothing to do also, since everything is connected to
emulation hardware which presents plain old view of control units, path,
devices, etc.
Last, but not least: I wouldn't afraid of such configuration, unless
other user of AMS are irresponsible. They could accidentally erase your
disk space or simply overload the array with very important data
processing like powerpoint presentations or AVI files. <g>
SAS interface has nothing to do with the above.
--
Radoslaw Skorupka
Lodz, Poland
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BRE Bank SA
ul. Senatorska 18
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wpacony) wynosi 118.763.528 zotych. W zwizku z realizacj warunkowego
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