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]
(See mail header or public key servers for PGP2 and GPG public keys.)
--- linux-2.2.13p16.work/drivers/scsi/hosts.h.orig Tue Oct 12 19:48:18 1999
+++ linux-2.2.13p16.work/drivers/scsi/hosts.h Wed Oct 13 12:32:11 1999
@@ -484,10 +484,10 @@
#ifdef CONFIG_SCSI_PLUTO_MODULE
#define SD_EXTRA_DEVS 40
#else
-#define SD_EXTRA_DEVS 4
+#define SD_EXTRA_DEVS 21
#endif
-#define ST_EXTRA_DEVS 2
-#define SR_EXTRA_DEVS 2
+#define ST_EXTRA_DEVS 3
+#define SR_EXTRA_DEVS 8
#define SG_EXTRA_DEVS (SD_EXTRA_DEVS + SR_EXTRA_DEVS + ST_EXTRA_DEVS)
#endif
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