Re: Building Big Ass Linux Machine, what are the limits?

Vladimir Dergachev (vladimid@red.seas.upenn.edu)
Fri, 25 Sep 1998 17:15:01 -0400 (EDT)


There is a company that makes big scsi cubes with a lot of drives
that connect to a scsi controller.. I think they have both raid
and capacity inside (up towards terabyte or so..)

Vladimir Dergachev

On Fri, 25 Sep 1998, Gregory Maxwell wrote:

> On Thu, 24 Sep 1998, Jim McQuillan wrote:
>
> > Hello all,
> >
> > I need to build a big machine to replace a
> > Compaq Proliant running SCO OpenServer.
>
> Okay.
>
> > The system needs to run several Progress databases (12gb and growing)
> > and I am
> > looking for maximum disk throughput for about 150 users accessing via
> > Telnet.
>
> Alright.
>
> > Some are telling me that I should be looking at big hardware, such
> > as HP9000, SGI or Sun. The type of equipment that would cost upwards of
> > $100k.
>
> You prob would be better off with one of those.. Not because of Linux more
> because of x86 hardware. But for the money....
>
> > I want to try it with Linux.
>
> Great.
>
> > Here are my preferences:
> >
> > - Intel 450 Single or Dual, the application is really NOT cpu bound.
> > I need Intel because until Progress releases a Linux version
> > I will be using the SCO version with iBCS. And, as a safety net,
> > if Linux isn't stable in this setup, I can put SCO on it
> > (I really don't want to do that).
>
> I'd get a single in a dual board. The dual boards tend to be of a higher
> quality too.. If this is going to be occuring a few months into the future
> (like when kernel 2.2 is out) then I'd say go with dual.
>
> > - 512mb ram. Can I go bigger?, whats the max?
> > Current system has 512mb and is only using about 300mb of it.
>
> I think you'll find Linux to use less memory then SCO. Still, you should
> be able to goto at least a gig in most high end boards today if you use
> 256meg dimms. Keep expandibility in mind. I highly recommend ECC memory as
> there is almost nothing worse then trying to track down a intermient
> memory problem that is silently corrupting memory.
>
> > - 4 Adaptec 2940UW Host adaptors with 4-4gb Ultra wide disks on each.
> > 16 drives total. Isn't there a limit on number of scsi disks?
> > If there is a limit, I could change it to a total of 8 9gb drives.
> > Progress has it's own Multi-volume support and can utilize as many
> > drives as I can give it.
> > I figure: more spindles + more heads = better disk performance.
>
> Well there is a limit of 16 but you can hack it to increase it. Someone
> else here should have more info.
>
> About Progress' multi volume support? Does it stripe your data across
> volumes?
>
> Do you realize that you have NO reduncy and if a drive flakes out, it all
> goes up in smoke?
>
> Do you need 64gigs of storage? or would 32 do? I would recommend putting
> those 16 drives (use 10,000 or at least 7,200 rpm ones) on a nice
> multichannel raid controller (I've used DPT if you use them get the high
> end model, I've also heard ICP Vortex is nice).... Set it up in a Raid-0/1
> array. This gives you the best possible performance, and reduncy at the
> price of 50% of your storage. (but it's fast as hell)
>
> > Is Linux ready for the Enterprise Server market?
>
> I feel that it is. I've implimented some really big Linux instlations and
> I've certantly had no more problems with Linux then a simmlar sized novell
> instlation. (and the Linux problems are MUCH easier to solve).
>
> > Will I run into a maximum on the number of processes that can run?
> > I have about 45-60 days to do this, Should I be waiting for the 2.2
> > Kernel
> > or do you think the latest 2.0.xx kernel can handle it?
>
> Personally, I think you should hold out for 2.2 if possible. There are
> just so many improvements..... But.. I do think that 2.0 could work for
> you. There are some 2.0 advantages (which will prob not live long after
> 2.2 but) like there is a patch to allow processes to have upto 30k file
> descriptors.
>
> I think the 2.0 kernles used a hardware context switch that was limited to
> 4096 processes.. Though there are prob patches to get rid of this limit.
>
> > I was hesitant about posting to the kernel list, but I figure that it is
> > the
> > kernel that has to handle the load, and I really need to know that Linux
> > can
> > handle this before I convince the customer to spend the money on the
> > hardware.
>
> :)
>
> > If this works, I have several other customers who would also be good
> > candidates for a Big Ass Linux Machine.
> >
> > Thanks for any suggestions you may have.
>
>
>
>
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