Re: Would a 2nd processor really be a waste of time???? help
From: Brian K. White (brian_at_aljex.com)
Date: 07/17/03
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Date: Thu, 17 Jul 2003 00:46:27 -0400
On Wed, 16 Jul 2003 18:18:03 +1200, Lee and Nadine wrote:
> We are looking at different aspects on what to do about our older unix
> sco 5.5 server that tends to run slow at times (333mhz with 196 meg
> ram). using cpqmon it shows the CPU "2 sec avg" the "10 sec avg" and
> the "20 sec avg" as maxxed out when things run slow. One idea was to
> buy another processor and more ram, however this is what one supplier
> has told us - see below. I have no idea if what he is saying is correct
> of if hes trying to drum up more sales. Some ideas on what he wrote
> would be greatly appreciated.
>
> As quickly discussed on the phone today the server is dual processor
> capable.
>
> Your server has only 1 processor.
>
> Memory is not an issue unless the system is swapping , if this was the
> case on your system you would not be able to login.
>
> Your system is not swapping and so is not the cause of the slow system.
>
> The server is only 333 MHz, what would a 5 year old 333 MHz PC with 75
> users logged in run like?
>
> The Unix system takes full advantage of Symmetric Multi Processing when
> the SMP license is installed.
>
> The only advantage of this would be seen when the system as it stands
> gets processor bound and slows down , with dual processors the load is
> shared and this processor bound state takes a little longer to occur .
>
> A second processor does not speed up a server but shares load at current
> processor speed. i.e. 333Mhz
>
> It should be noted that even with a second processor the system may
> become processor bound very quickly.
>
> Estimated Pricing:
>
> SCO Unix SMP License
> $2,900
>
> Second 333 MHz Processor [ subject to availability] $1,000
>
> Installation approximately 2 days labour [ out of hours rate ] $ 2,400
>
> Plus travel and accommodation
>
> Estimated pricing does not include GST.
Holy cripes!!!
a 333mhz anything, even a xeon, sould be at _most_ about $75(US)
installation including changing the bios settings and installing the smp
license and even including the possible backing-out of several sco patches
and suppliments so that they can be re-added after smp is in, should only
be a couple hours. 4 maybe if you run into some unforseen problem that
takes a whoile to figure out or simply abandon the attempt and revert. add
a coupel more if you want to be extra safe and do a full backup first, but
since you should have one of those every night anyways, I wouldn't even
bother. it's not an especially risky operation. (although, anyone who says
it takes two days may not be of the competence level where they know how
to make a copy of the current good kernel and if necessary boot from it
later, so for them, if the box doesn't boot after installing smp and the
only way they know to fix it is something collosally overkill like
restoring the whole drive from a tape... yeah for them it might take two
days.) add another hour for standing around testing and listening/watching
for problems after you go back to work. I'd porbably stand around about 15
minutes myself. most problems will either show up immediately, or else
there is no predicting and no sense waiting.
I have no idea what an smp license costs but that you can find on-line
many places, because lost of people sell it and it doesn't matter who you
get it from. the only value a vendor could add to make his price worth
more is if he is knowledgeable he can assure that you buy the right
license and nothing you don't need. It is confusing in some cases and so
this service is actually valuable in some cases. Yours is not a complex
licensing problem though.
your cpu is old enough that you should actually be able to get two
matching faster cpus for $200(US) or so all together. This would require
knowing the exact motherboard model and revision, and bios version, and
probably installing a bios update from the motherboard manufacturer to
support faster cpu's than it originally could. I've done it plenty of
times and all that would be part of the same couple hours I said above.
you have other speed limits on a box that old, probably the scsi card is
not a high-end raid card nor ultra160 discs. probably the ram is 66 mhz
sdram
The second cpu will probably help ...somewhat. probably not what you'd
call "a lot". No particular job will go any faster, but, the box as a
whole can support almost twice as many jobs at any one time as it could
before. There is some overhead managing two cpu's though, so sometimes
it's really more like 1.5 to 1.8 times as many jobs instead of the
theoretical 2.0 times as many jobs.
This will make everything faster, just by making them _possible_ at times
when some big job would have normally tied up your only cpu. All in all
I'd say it was worth doing, being cheaper faster and easier than getting a
new server, but not at the quoted prices. at those prices you might as
well get a new server because even though that would definitely be a lot
more, at least you know about how much faster it will be. Beware you would
need to upgrade your version of OS to at least 5.0.6 in order to use any
P4 based cpu.
The ram/swapping/not-swapping argument is not quite true either. If
nothing else, you can probably get a noticeable boost by adding more ram
even if all you do with it is max out the disk buffer cache size kernel
parameters. (giving yourself 450 megs of disk cache). going too far in
this direction can hurt performance too, because every few seconds the OS
flushes the cache, and it takes a lot longer to flush 450 megs than say,
20. there are other tunable parameters that control how often and at what
threshold the cache is flushed which might make the extremely large cache
work out, but it depends on your actual usage pattern which I cannot
guess. that requires some live testing and observation. (_THAT_ can easily
take two days, or two weeks or two months... but somehow I don't get the
impression their quote figured in anything like that.) enabling sar is a
good start. installing sarcheck is another.
to summarize:
You'll get more of a boost with new cpu, new motherboard and new ram (ddr
or rdram at high bus rates, not sdram), which will also require an OS
upgrade.Even if single-cpu, just because the cpu and memory are so much
faster.
You'll get a good noticeable hike by adding a second cpu to existing
system, especially if the motherboard can take faster cpu's and you
replace both rather than add one. (the same applies to the ram, maybe the
motherboard can be made to use pc100 or even pc133 sdram instead of 66? It
*should* be a lot faster easier and cheaper to do this than set up a new
server, but the quotes you received are not good enough to make it worth
doing in my opinion. Perhaps another consultant in your area?
there are other issues that make a huge difference that might be worth
looking at too. what kind of hard drive do you have now? Replacing a 20 or
40 mhz scsi drive & controller with a 10k or 15k ultra160 drive and
ultra160 controller makes a big difference. stepping up to raid
even more so, but then it gets expensive. :) It's a time consuming job
swapping hard drives and controllers. coupled with the cost of the
hardware itself, it's probably too much to be worth doing because the
amount of improvement is not as sure.
> As discussed this is not a very good idea due to the small possible
> advantage it may bring during peek usage and cost benefit. Even after
> installation you may find that there has been no improvement in
> performance .
>
> Again as mentioned on the phone we need to get the new server installed
> as soon as possible so users can benefit from superior technology
> enhancements of the past 5 years.
-- Brian K. White -- brian@aljex.com -- http://www.aljex.com/bkw/ +++++[>+++[>+++++>+++++++<<-]<-]>>+.>.+++++.+++++++.-.[>+<---]>++. filePro BBx Linux SCO Prosper/FACTS AutoCAD #callahans Satriani
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