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Hi Augie,
( I presume you do indeed mean ESCON (not Ficon, because the rules all change then)
we run two sites 35 Km apart each with a Z/800 and escon attached HDS 9980V ( I am sure SHARKS would be the same) . Before the HDS boxes we had RAMAC-2 dasds and subsystems, and before them we had 3390s and 3990s ( and 9672s and escon-equipped 3090-17ts).In all cases, each site's cpus accessed the other site's dasd via escon. we did need 9033 escon directors at each site with a 9036 in the middle ( fibre provider's requirement that was) the escon talked to each other via laser escon ( that is what gave us the distance) over that dark fibre. Now, we use a DWDM , and it handles the distance side of things and that escon directors now talk directly to each other over the DWDM via LED ports ( were it not for the fact that they are really handy boxes anyway, we would not need them any more, since the DWDM handles the distance isse now).
We have always been happy with this arrangement, but I must warn about a nasty little thing called escon 'DROOP' (lovely name).
Because Escon is what is called a 'CHATTY' protocol its USEFUL data rate slows down a lot, the further you go with it. In our case (with our typical disk blocksizes of 4KB) the intersite disk traffic runs at about 1 MB/sec, ( we got 4.5 from the LOCAL RAMACS, and of course much more from the 9980Vs ( or sharks, I am sure). I think it would start getting even worse if the sites were much further apart... ( Einstein has a lot to answer for!!!)
I repeat this droop is an ESCON design attribute, not FICON or native fibre.
I hope some of this helps ... Phil Steele
-----Original Message-----
From: owner-vse-l@Lehigh.EDU [mailto:owner-vse-l@Lehigh.EDU]On Behalf Of
August.Carideo@avon.com
Sent: Friday, 21 January 2005 4:00 AM
To: VSE Discussion List
Subject: ESCON distance
Does anyone know if there is a distance restriction for a ESCON channel
from a Z 800 to SHARK dasd, If there is does anyone know what it is, or
where
I can get specs on it ?
Also if I remember correctly there was some kind of channel extender
thanks,
Augie
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