Re: Suggestions wanted

[David Brownlee <abs%netbsd.org@localhost>]

On Thu, 28 Sep 2000, John Klos wrote:

> Hello, all,
> 
> My machine is a CyberStorm PPC with a 66 mhz 68060 and two IBM 18 gig 
> 10k wide ultra SCSI drives; I am running NetBSD 1.4.2.
> 
> (one) In order to reduce thrashing, I have decided to have my root, 
> swap, and /usr/web on the first drive, and var, usr, and additional 
> swap on the second.
>       (a) is this ideal for a heavily used web server?

        Seems reasonable. You want to split the heavily used partitions -
        probably website vs weblogs + others. If you have the space its
        definitely worth putting swap on both drives (see next).

>       (b) can I prioritise the swap, and if so, which drive should have it?

        See swapctl(8) - you can set priority=N. Start off by setting
        them both to 0, then watch the disk usage under load with
        'iostat 5'. If one disk is more heavily used, set its priority
        to a higher number. Monitor again with 'iostat 5' to make sure
        you make the right choice :)

> (two) Apache, with mod_perl installed, takes about 3300k per daemon. 
> Should I limit the maximum number of connections to 40 in order to 
> keep them from thrashing swap, or can I assume that the "active" part 
> of each daemon is probably much less, and leave the maximum somewhere 
> at around 100? (I've had more than 70 spawned at a time during busy 
> web traffic, but this was before mod_perl)
> 
        I would expect much of that to be shared between processes
        (executable code and unmodified data). Try generating load
        ideally from another machine ('ab' may prove useful), with
        the maximum number of connections set to various values,
        to get a feel of how it performs.

> (three) Regarding memory, I have 128 megs of 64 bit ram on the 
> CyberStorm, and I have 16 megs on the motherboard. Knowing that 
> motherboard memory is substantially slower than accelerator memory, 
> should I remove it, or can I have NetBSD use it for some other 
> purpose? I vaguely remember m68k Linux having a way that the 16 meg 
> could be used as swap.
> 
        I do not believe NetBSD currently supports using part of
        the memory as swap, though it would certainly be a nice
        addition if someone wants to contribute the code :)

> (four) Also regarding memory (this is a long shot): Has anyone heard 
> of or does anyone know of any way to get a CyberStorm to recognise 
> 128 meg SIMMs? I have two 128 meg SIMMs in my Blizzard 1260, but when 
> I put them on the CyberStorm, they appear as only 32 megs each.

        Uh, pass...
        
        One final thought - you might want to look at NetBSD 1.5_ALPHA2.
        I'm running here in production use on i386 and sparc boxes and
        finding it better than 1.4. Enabling softdep on filesystems has
        been a big win in particular (only benefits write performance,
        plus read when its being held up by writes :)

                David/absolute
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