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Software - MPE/iX 7.0 Operating System (1.13 mb)
Software - MPE/iX 7.0 Operating System (220.81 kb)
Anleitung Zusammenfassung
Routers are cautious and like to form a consensus of how to "map" all the
devices visible in the FC-SAN. If two Routers can communicate they WILL
exchange maps. If the maps to not agree then what the Routers think is the
"older" map will be invalidated. You will then be forced to MANUALLY reset
the Router with the "invalid" map. If a Router can "see" a device port
through any set of FC connections than it can and will communicate with any
other Router that can "see" the port. This is true even if there are no LUNs
configured on that port! Therefore your best path to success is to limit the
number of Routers connected to any device port and the best mechanism for this
is FC Switch "Zoning".
Tip #1:
FC Switch Zoning, your best friend.
Any FC Switch worth anything allows you to "Zone" the ports on the switch.
That is logically group a sub-set of ports such that devices connect to ports
outside the group/Zone cannot communicate with the devices inside this Zone
and vice versa. (A "Switch" without Zoning is really a "Hub". Hubs, though
they work, should be avoided as they leave you open to too many problems.)
Your absolute safest and best Zone configuration is one with two Ports, one to
connect to a Router and one to connect to a Device Port. This will prevent
this Router from talking with any other Router or Device Luns on any other
device port.
"Ah," you say, "but, I can have multiple routers in my zones because I'll use LUN Security to
virtually link the Router to my Device LUN". WRONG!
Tip #2:
LUN Security: tricky and best avoided.
LUN Security is a feature of most Storage Devices that allows one to limit
the visibility and availability of a particular Device LUN to a single
accessing device. This is generally accomplished by a entering an FC-SAN
hardware unique address (a.k.a. WWN) into a Device dependent configuration
tool. Routers do have WWN values which can be used. Sounds good, but
don't forget 'Really Surprising Fact #1: Routers "talk" to other Routers.'
Consider this scenario:
You create six LUNs on a Device Port.
You connect two Routers via a Switch to the Port.
You configure three LUNs to Router One WWN and three to Router Two WWN.
If you turn on Router One it will see its three LUNs. Turn it off.
If you turn on Router Two it will see its three LUNs. Leave it on.
Turn on Router One. It will see its three LUNs AND talk with Router Two.
Router Two will notice it's map is out of date BECAUSE it CANNOT "see"
the LUNs that Router One can see.
Router Two map is marked invalid.
If you "Manually Reset" Router Two it sees its three LUNs and Router One
map will be marked invalid.
Repeat ad nauseum.
Simply put: You CANNOT use LUN security to limit the view of LUNs to Routers
that connect to the same device port. The ONLY time LUN Security can be used
is if there is ONE and only ONE Router connected to a Device Port (either
directly or via Zoning).
Really Surprising Fact #2:
Windows systems can now STOMP on MPE/iX disks.
Various versions of "Windows" type systems have a "Disk Administrator" tool
(windisk.exe, diskmgmt, etc.) During boot if "new" disks are discovered it
will give you the option to "claim" the disk. NEVER do this unless you are
willing to risk loosing data! If given the option disable this "feature."
...Dieses Handbuch ist für folgende Modelle:
Software - MPE/iX 7.5 Operating System (480.09 kb)