Stupid me -rasselfrassen SCSI terminator!

[CMonster]

I always thought my Ultra SCSI 160 was a little slow and lately I noticed it showed "40" on boot, I thought it was the Quantum Atlas V drive that was the problem ....stupid me! I still had the terminator on the cable from when I was using an Ultra Wide 40mb/s card and it was limiting the drive to 40mb/s believe it or not ....

I did some reading, and after removing the terminator -well, it says "160" on boot and it certanly seems about twice as fast ....argh! How could I have deprived myself so long!!!!

Ha! my ATA100 drives are no longer faster!

[Richard_Cranium72]

Good info to know.

My old HP SCSI Scanner card by Symbios Logic does NOT require a terminator either.

Makes me wonder why the things even have them if it's not necessary.

[otheos]

Ha! my ATA100 drives are no longer faster!

Hm, I doubt they were ever faster than the Atlas V (even when limited at 40MB/s).

As for a performance increase, if the Atlas is the only drive on the chain I don't see where the difference comes from as the Atlas V has an STR of 26MB/s so 40MB/s would give plenty of bandwidth. If you got another drive there it's a different story.

Still the higher bandwidth is better.

[CMonster]

otheos - you're right in saying that the Quantum drive was probably very fast anyway, it was, that is why I didn't notice much difference between the ultra wide adapter and the Ultra160, but on working with small files it always seemed that my ATA100 systems were a bit faster and that bothered me.

Although I cannot account for the increased throughput, the maximum possible burst rate is obivously going to be different, even in spite of the fact that my 64bit PCI adapter card is sitting in a 32bit slot. The benchmarks in Sisoft Sandra were like night and day, though I understand that Sandra is not the best for benching SCSI drives.

I was using an active terminator which was necessary with my old adapter but aparently is not to be used with LVD drives and SCSI 160 -Both the drive and the cable were SCSI 160 prior to swapping out the adapter card -us poor people have to upgrade one component at a time ya know http://www.sysopt.com/forum/wink.gif

[CMonster]

Not terminated and kicking but! ..but then there is only the one drive on the cable, I wonder if that makes the difference?

[otheos]

Not using termination may or may not work. If it works for you, then well there's no law against it http://www.sysopt.com/forum/smile.gif

Enjoy it!

[otheos]

CMonster,
I'm confused, you mean that your LVD chain is not terminated now? cause it should. And since as you know the Quantum V has no termination jumper you need an active LVD terminator at the end of the cable.

As for the speed difference, yes small files that move from and to the drive cached will show up the change in bandwidth.

The Quantum Atlas V has a maximum STR of 26MB/s. Now newer 7200rpm IDE drives have STRs as high as 40MB/s.

The Maxtor DM+ 60 for insance, has 39MB/s.

But look at these graphs:

The Maxtor:
<IMG SRC="http://131.251.45.109/up/maxtor.png" border=0>

Average STR 31MB/s read, 20MB/s write, and ~9ms access.

Now look at the Quantum Atlas V:

<IMG SRC="http://131.251.45.109/up/quantum.png" border=0>

Average STR 23MB/s read, 17.5MB/s write and ~6ms access.

The Quantum is 2 years older, yet has similar write STR and with the lower access it will feel (and be for most uses) faster!

[CMonster]

Yeah - I know what you mean, it should be terminated. It's weird that it's working.

My problem is that I can find Ultra SCSI 160/LVD cables with built-in termination ($50-$88 -ouch!), and I can find Ultra SCSI 160/LVD cables w/o termination (I have one).... but I can't seem to find just the internal terminator. If I put the active terminator from my old SCSI card it drops the drive down to 40mb/s -this also happens if you use an older SCSI device on the LVD chain and is well documented on the Adaptec site. So, now where can I get a cheap LVD terminator?

[This message has been edited by CMonster (edited 09-06-2001).]

[otheos]

Yes you need an LVD terminator. Ask at www.storagereview.com (http://www.storagereview.com) forums and I am sure you'll find a good deal.