mirrored vs. duplexed SCSIs
stagger
I (over)built a replacement 3.12 server that is, as yet, not in
production. It has two duplexed drives, just like the old server. I'm
a little disapointed with some cusory disk tests, since the new machine
has an adaptec 29160 with 2 red hot 10,000rpm 9G IBM drives . Is
duplexing much faster? The price of another 29160 faster I guess is the
question?
TIA
S
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Felton Green
Duplexing can be faster IMO since data can be retrieved from both drives at
the same time. It can be tiresome to get the system "tweaked" though. I like
to start with the basics and work up from there. Teflon and gold cables also
help quite a bit. Stabilant 22 works too. What kind of drives? IBM has had
"some" problems with certain types of drives.
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stagger
> Duplexing can be faster IMO since data can be retrieved from both
> drives at
> the same time. It can be tiresome to get the system "tweaked"
> though. I like
> to start with the basics and work up from there. Teflon and gold
> cables also
> help quite a bit. Stabilant 22 works too.
What kind of drives? IBM
> has had
> "some" problems with certain types of drives.
ST39102LWs (BTW I assume 128M of RAM is sufficient with two 9 gig
drives)
Felton Green
128 MB for 9 gig of volume space is fine.
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Barry Schnur
driver are you using for the 29160?.
Personally, I'd have gone with the TekRAM DC390U2W -- a lot less money.
For 9G of volume space, 128M is fine.
Barry Schnur
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stagger
> Those are good enough drives that if duplexed should provide
> decent performance -- what
> driver are you using for the 29160?.
> Personally, I'd have gone with the TekRAM DC390U2W -- a lot less
> money.
Barry Schnur
OK -- question might be about specific version of it.
>> Personally, I'd have gone with the TekRAM DC390U2W -- a lot less
>> money.
>Well, I'm sure this discussion will be helpful for others! :-)
>
Understood.
I sometimes look at Adaptec as the Microsoft of SCSI adapters...
Felton Green
LOL... but they ( Adaptec ) put out a good product. 8- )
Barry Schnur
Mostly, though definitely overpriced.
Shaun Pond
> It has two duplexed drives
>
not yet it doesn't, it has two mirrored drives, if they're on the same
controller! Duplexing will be faster, and don't forget to add
SET ENABLE DISK READ AFTER WRITE VERIFY=OFF
in your startup.ncf
Shaun Pond
Novell Support Connection SysOp
Mike Jacoubowsky
learned long ago about the incredible differences when mirroring with
SET ENABLE DISK READ AFTER WRITE VERIFY=OFF
With it set "on" it takes about 6 hours to re-mirror a hard drive. Off and
it takes about 40 minutes.
--Mike-- Chain Reaction Bicycles
http://www.ChainReactionBicycles.com
"Shaun Pond" <sh...@sysop.nsc> wrote in message
news:VA.000020b...@sysop.nsc...
Shaun Pond
exactly - it's easy to forget, since that's the default with NW4/5...
stagger
> >> driver are you using for the 29160?.
> OK -- question might be about specific version of it.
12/03/99.
TIA,
Eric
stagger
> OK -- question might be about specific version of it.
it is dated 12-03-99 . . .
stagger
<sh...@sysop.nsc> wrote:
> Stagger,
> > It has two duplexed drives
> >
> not yet it doesn't, it has two mirrored drives, if they're on the
> same
> controller! Duplexing will be faster, and don't forget to add
> SET ENABLE DISK READ AFTER WRITE VERIFY=OFF
> in your startup.ncf
opinion, getting another card and duplexing would be nuch more speedy?
If the drives are just mirrored, does the setting write verify=off
improve performance alot?
TIA,
Eric
Barry Schnur
Shaun Pond
oh yes, I'd definitely recommend duplexing - with one controller,
mirroring is slower than just having one disk, as the controller has to
make two write requests,with duplexing they can take place
simultaneously! As for the SET parameter with mirroring, I have to say
I don't sure, but I would have thought so.
Paul Meiners
One of my clients with an older server had mirroring. Disabling "read after write" did speed up the
mirrored set.
I inherited this client, originally the read after write was enabled. Disk access improved after
disabling- the speed increase was (conservatively) >10 % . This was on an old 233 server Mhz server,
so it's hard to judge, but the directories came up faster, database programs ran faster. The client
noticed immediately.
Personally, my belief is in duplexing and raid arrays, the safety margin is worth it. In both cases
disk "reads" increase dramatically over mirroring.
As far as dissapointing cursory test results- the are many other factors affecting server
performance. I would suggest you read all the posts in the Netware 3 and even the Novell 4 forums
concerning performance ( not just in the storage media forum). Follow the the advice of Barry, Felton
and Shaun , in the posts, and you won't go wrong.
Paul Meiners