Just one thing to remind.
SAN is getting hot and Fibre Channel will play a great role there. For FC
environment, arbitrated loop will support up to 126 devices (target id).
Also some device will have huge LUN configuration such as EMC Symetrix, up
to 1024. When changing the default parameter, this should be under the
consideration.
Regards,
-eddie
-----Original Message-----
From: Kurt Garloff [mailto:[EMAIL PROTECTED]]
Sent: Friday, March 10, 2000 8:56 AM
To: Alan Cox
Subject: Re: SD_EXTRA_DEVS (was Problem)
On Fri, Mar 10, 2000 at 02:15:54PM +0000, Alan Cox wrote:
> Ok I picked roughly similar numbers. Can you tell me where you fished the
21
> out from and why (just curious)
I think I made it up somehow like this:
Going out from the current numbers, I was thinking about how many external
devices of that kind people might want to connect and ended up with smth
like 20, 3, 8 for sd, st, sr.
20 sd devs are 4 arrays � 5 disks
8 sr devs is a changer which uses 7 LUNs plus a CD-R
3 st devs: most changers just use one LUN for the tape access and as st
devs take up by far the most mem ...
This would result in 31 sg devs, but I like a number like 32 much better ...
so I increased one of the numbers by one. I think the tapes took the largest
amount of memory, so I added a sd dev. People with huge SCSI installations
mostly do it in order to connect a lot of disks (RAID arrays normallyy), not
because they have 8 tape devices, IME.
I don't have my notebook (one out of paper ...), where I put the notes for
the calculation of the needed mem that time, here at Univ, but I can look it
up, when I'm home again ... (but where I don't currently have mail :-(
> I'll probably change the 2.2.15 ones to match the SuSE ones. Mine are
similar
> values and we might as well just have one default size of extra devices
If you came to similar values, that indicates that they are in the region
for a reasonable compromise between saving resources (mem) and allowing for
easy extendability of the SCSI subsystem.
Of course, I appreciate, if you use the same numbers.
I attach the trivial patch ...
Regards,
--
Kurt Garloff <[EMAIL PROTECTED]> [Eindhoven, NL]
Physics: Plasma simulations <[EMAIL PROTECTED]> [TU Eindhoven, NL]
Linux: SCSI, Security <[EMAIL PROTECTED]> [SuSE Nuernberg, FRG]
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