*BSD News Article 59857


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From: casper@fwi.uva.nl (Casper H.S. Dik)
Newsgroups: comp.unix.bsd.netbsd.misc,comp.unix.bsd.bsdi.misc,comp.unix.solaris,comp.unix.aix
Subject: Re: ISP hardware/software choices (performance comparison)
Date: 17 Jan 1996 17:25:37 +0100
Organization: Sun Microsystems, Netherlands
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andrewg@microlise.co.uk   (Andrew Gierth) writes:

>There are so few tunable limits in AIX that it can be quite a shock
>to someone used to other Unix variants:

>  - maximum processes per user (this can be increased without a reboot)


This is a very common limit (found in SunOS 4/Solaris 2, but probably dating
back to BSD 4.x).  Can be changed on the fly, but the system won't
kill of the extra processes.

>  - maximum memory pages available for mbufs

Increasable?  Since Solaris 2.x uses the same memory for all
packets, an upperlimit on such buffers would do a lot of harm.

>AIX gets away with this because so much of the kernel is pageable
>(on systems I've looked at, something like half of the total kernel
>memory usage, but will vary).

You don't necessarily need a pagable kerenl for all this, but having
enough virtual memory to play with is important.  The old BSD way of
having to take kernel virtual memory out of the user address space
hurts badly on larger systems, that's why the UltraSPARC  machines
no longer do so.  A pageable kernel is a good idea, but it does
require some careful thought.

Not having to tinker with share memory parameters would be nice
to haev under Solaris 2.x.

>I've never used Solaris, but can it match this scenario:

>Assuming that hardware can be hot-swapped, it is (I think) possible
>with AIX to install an entirely new disk device (for example), for
>which drivers were not previously on the system, load the necessary
>drivers, configure the new device, migrate logical volumes from
>existing disks to the new device, take the old disks offline, remove
>their drivers (if appropriate), ALL WITHOUT DISTURBING THE USERS!
>[And without requiring any additional software!]

Adding disks and devices (if hotswappable) is not a problem and
I have done so in Solaris 2.x.  Because there's not really much hardware
support for this yet, it isn't officially supported and requires
you to run a program (drvconfig) by hand.  On the software side
the support is there, Sun doesn't yet deliver the hardware capable of
more interesting hotswaps than SCSI devices (and powersupplies on some
models)

Casper
-- 
Casper Dik - Sun Microsystems - via my guest account at the University
of Amsterdam.  My work e-mail address is: Casper.Dik@Holland.Sun.COM
Statements on Sun products included here are not gospel and may
be fiction rather than truth.