Very Computer

by **John Robins** » Sat, 07 Sep 1996 04:00:00

I've been asked to spec and build a fast database server machine
running Linux. I want to do a dual Pentium Pro, with all possible
go-faster stripes. I believe that Linux now supports RAID in software
- has anyone any experience of using that support?

Many thanks

John.
-- _ _

| |_| / . \ ' \| ' \ 5 Main Street, Auchencairn DG7 1QU, UK +44 1556640 390
\___/\___/_||_|_||_| On this particular occasion, I speak for the company

by **Dave Cine** » Fri, 13 Sep 1996 04:00:00

Quote:>I've been asked to spec and build a fast database server machine
>running Linux. I want to do a dual Pentium Pro, with all possible
>go-faster stripes. I believe that Linux now supports RAID in software
>- has anyone any experience of using that support?

No, but I use it with a DPT SmartCache 4 and Raid module.

I would have to recommend to anyone using RAID.....keep it in hardware.

----------------------------------------------------------------------------

Dave 'Kill a Cop' Cinege (aka Psychopath #3) --- Super Genius at Large
http://www.psychosis.com/ Happiness is a full bag of 34-0-0.....

Harry Browne for President in '96 Libertarian Party 1-800-682-1776
http://www.HarryBrowne96.org/ http://www.lp.org/

by **Keith Smi** » Fri, 13 Sep 1996 04:00:00

>>I've been asked to spec and build a fast database server machine
>>running Linux. I want to do a dual Pentium Pro, with all possible
>>go-faster stripes. I believe that Linux now supports RAID in software
>>- has anyone any experience of using that support?

>No, but I use it with a DPT SmartCache 4 and Raid module.

>I would have to recommend to anyone using RAID.....keep it in hardware.

I ditto this sentiment.

And the DPT RAID controllers are not all that bad price-wise either, Not
to mention the cache benifits, etc.

It's a question of "spare" CPU cycles. If you have excessive CPU cycles
to spare you can do all of this stuff on your host CPU without noticing,
but the minute your system CPU load exceeds available cycles you are
burning CPU cycles on RAID/Cache management that could be used by an
application if you just dumped the data off to a smart RAID/CACHE
controller.

Which sounds like it's OK as long as you have an incredibly fast CPU,
BUT! The problem is peak loading, because generally speaking if you are
beating the hell out of your disks your beating up your CPU also.

It's a pretty simple concept that the "Memory is more useful on the
host CPU, than a caching disk controller" don't seem to understand.
Their argument is TRUE but only when your CPU has idle cycles to spare.
--

Digital Designs (910) 423-7389/7391 [V.34]
PO Box 85
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by **Dave Cine** » Tue, 17 Sep 1996 04:00:00

>>>I've been asked to spec and build a fast database server machine
>>>running Linux. I want to do a dual Pentium Pro, with all possible
>>>go-faster stripes. I believe that Linux now supports RAID in software
>>>- has anyone any experience of using that support?

>>No, but I use it with a DPT SmartCache 4 and Raid module.

>>I would have to recommend to anyone using RAID.....keep it in hardware.

>I ditto this sentiment.

>And the DPT RAID controllers are not all that bad price-wise either, Not
>to mention the cache benifits, etc.

>It's a question of "spare" CPU cycles. If you have excessive CPU cycles
>to spare you can do all of this stuff on your host CPU without noticing,
>but the minute your system CPU load exceeds available cycles you are
>burning CPU cycles on RAID/Cache management that could be used by an
>application if you just dumped the data off to a smart RAID/CACHE
>controller.

I consider performance a side issue. The main thing for me is crossplatform
compatablity.

I run RAID 0 and use OS/2's bootmanager to boot DOS, OS/2 and Linux.
If you go software that RAID will only work with THAT OS and THAT software.
With hardware, it runs with any OS that works with the SCSI controller.

----------------------------------------------------------------------------

Dave 'Kill a Cop' Cinege (aka Psychopath #3) --- Super Genius at Large
http://www.psychosis.com/ Happiness is a full bag of 34-0-0.....

Harry Browne for President in '96 Libertarian Party 1-800-682-1776
http://www.HarryBrowne96.org/ http://www.lp.org/

by **Roger Boo** » Thu, 19 Sep 1996 04:00:00

: >>>I've been asked to spec and build a fast database server machine
: >>>running Linux. I want to do a dual Pentium Pro, with all possible
: >>>go-faster stripes. I believe that Linux now supports RAID in software
: >>>- has anyone any experience of using that support?
: >>
: >>No, but I use it with a DPT SmartCache 4 and Raid module.
: >>
: >>I would have to recommend to anyone using RAID.....keep it in hardware.
: >
: >I ditto this sentiment.
: >

And again. I at one point ran tests of Suns DiskSuite on a Sparc 20 with
Dual 120 (I think it was 120 anyway) processors. The machine didn't
even work with reasonable speed as an NFS server, much less running
applications.

As a recommendation, at the time we found the SCSI RAID controller from
a company from Tiawan (Rose Data Systems) screamed, was relatively
inexpensive, and used standard SIMMs. I never actually tried any of
the PC RAID controller cards.

Roger

by **John Robins** » Sat, 21 Sep 1996 04:00:00

Roger Books writes:

>: >>>I've been asked to spec and build a fast database server machine
>: >>>running Linux. I want to do a dual Pentium Pro, with all possible
>: >>>go-faster stripes. I believe that Linux now supports RAID in software
>: >>>- has anyone any experience of using that support?
>: >>
>: >>I would have to recommend to anyone using RAID.....keep it in hardware.
>: >
>: >I ditto this sentiment.
>: >

>And again.

I've taken on board all that has been said here (and emailed to me)
and I've decided to go for the hardware solution, largely because of
the lack (at the moment) of RAID5 support in Linux. I saw the software
overhead of striping (RAID0) as a minimal one, with the benefit of
reduced average seek time under load (I have a friend who, it turns
out, has his swap space striped across discs). The machine I'm
building is to be a database server, and so I saw the disc system as
the bottleneck, not the processor (especially with all THAT processing
power). Part of the original spec was '...and do it as cheaply as
possible', but that condition has been relaxed in favour of
reliability (the RAID5 requirement), so we're just trying to pick a
card now (looking like the Adaptec 3985UW, but you folks seem to like
the DPT and Buslogic cards, so I'll be getting more info on those
too).

Many thanks, all!

John.
-- _ _

| |_| / . \ ' \| ' \ 5 Main Street, Auchencairn DG7 1QU, UK +44 1556640 390
\___/\___/_||_|_||_|
I'm goin' fishin'... Gonna bait me a line... --Chris Rea

by **John Robins** » Sat, 21 Sep 1996 04:00:00

Reposting article removed by rogue canceller.

Roger Books writes:

>: >>>I've been asked to spec and build a fast database server machine
>: >>>running Linux. I want to do a dual Pentium Pro, with all possible
>: >>>go-faster stripes. I believe that Linux now supports RAID in software
>: >>>- has anyone any experience of using that support?
>: >>
>: >>I would have to recommend to anyone using RAID.....keep it in hardware.
>: >
>: >I ditto this sentiment.
>: >

>And again.

I've taken on board all that has been said here (and emailed to me)
and I've decided to go for the hardware solution, largely because of
the lack (at the moment) of RAID5 support in Linux. I saw the software
overhead of striping (RAID0) as a minimal one, with the benefit of
reduced average seek time under load (I have a friend who, it turns
out, has his swap space striped across discs). The machine I'm
building is to be a database server, and so I saw the disc system as
the bottleneck, not the processor (especially with all THAT processing
power). Part of the original spec was '...and do it as cheaply as
possible', but that condition has been relaxed in favour of
reliability (the RAID5 requirement), so we're just trying to pick a
card now (looking like the Adaptec 3985UW, but you folks seem to like
the DPT and Buslogic cards, so I'll be getting more info on those
too).

Many thanks, all!

John.
-- _ _

| |_| / . \ ' \| ' \ 5 Main Street, Auchencairn DG7 1QU, UK +44 1556640 390
\___/\___/_||_|_||_|
I'm goin' fishin'... Gonna bait me a line... --Chris Rea

by **Sean Reifschneid** » Sun, 22 Sep 1996 04:00:00

>And the DPT RAID controllers are not all that bad price-wise either, Not
>to mention the cache benifits, etc.

Define "not all that bad price-wise"... It seems like they're around
$1K when I can even find them... I had seen one place with them that
seemed to be about $350 without any cache memory, but the DPT home-page
didn't list that card at all. So where can I find one that's not
$1K?

Quote:>It's a question of "spare" CPU cycles. If you have excessive CPU cycles
>to spare you can do all of this stuff on your host CPU without noticing,

Beyond "spare CPU cycles", I've found that most hardware RAID implementations
seem to be more reliable than software implementations... Specifically
on HP machines running "mirror-disk".

Also, I was looking at the ASUS home-page, and they have a RAID controller
listed that has a 486SX processor on it, and two narrow SCSI channels,
and you can upgrade it to a total of 4 narrow SCSI channels. Sounds pretty
impressive, but I'm sure there aren't any drivers for Linux out...

Sean
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by **Simon Hobs** » Wed, 09 Oct 1996 04:00:00

> I've taken on board all that has been said here (and emailed to me)
> and I've decided to go for the hardware solution, largely because of
> the lack (at the moment) of RAID5 support in Linux.
snip
> Part of the original spec was '...and do it as cheaply as
> possible', but that condition has been relaxed in favour of
> reliability (the RAID5 requirement), so we're just trying to pick a
> card now (looking like the Adaptec 3985UW, but you folks seem to like
> the DPT and Buslogic cards, so I'll be getting more info on those
> too).

You need to look carefully at the Adaptec card as (IIRC) it only has raid
support for Netware (or it did when I last looked). I don't know whether it
works at all (or will simply appear as three 2940 controllers) under Linux.

TTFN, Simon

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