Finally got a SCSI drive! Need some advice

Jester · Post by **Jester** » Wed Jan 08, 2003 1:04 pm

Well I finally got fed up with IDE and decided to get a 10k rpm SCSI drive. I got a brand new 9.1GB Seagate Cheetah 18XL (ST39204LC) off eBay for $30. Here's a link to the specs. http://www.impediment.com/seagate/s2000 ... 04lc.shtml

The drive is listed as 80-pin U160. I'm going to hook it up to the 68-pin channel on my UW controller. What kind of convertor will I need? Will this convertor I found on eBay work?

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 2085971596

Also what is LVD? I was always under the impression all 80-pin drives were LVD?

Thanks!
-Dave

DocSilly · Post by **DocSilly** » Wed Jan 08, 2003 1:39 pm

That SCSI drive isn't quite new, it was introduced beginning of 2000. A new 7200 IDE drive is pretty much equal or faster in most categories.

The drive is listed as 80-pin U160.

That's a so called SCA interface.
SCA stands for "Single Connector Attachment". It is a standard being worked on by the ANSI Small Form Factor (SFF) committee. It combines WIDE SCSI signals, Power connections and ID switch connections onto one connector.

The main reason for creating this standard was to make it easier to connect drives in a hot-swappable RAID configuration. SCSI vendors sell adapters that bring out the three sets of signals to conventional connectors.

Also what is LVD?

Low Voltage Differential is a new hardware bus driver type for SCSI-3. It first becomes important with Fast-40 (Ultra2) devices. If single ended (S.E.) bus drivers were used with Fast-40, the bus length would be limited to about .75 meters! Since this was clearly un-acceptable, and the older High Voltage Differential (HVD) interface adds too much cost to a system, ANSI defined a new form of differential interface that is less expensive to implement because the bus driver logic dissipates little enough power that it can be included in LSI chips. They also wanted to make sure they avoided the confusion caused by HVD (HVD and S.E. devices cannot co-exist on a bus), so they specified that if an LVD device is designed properly, it can switch to S.E. mode and operate with S.E. devices on the same bus segment.
Another difference worth noting is that LVD devices do not contain on-board terminators. You need to attach an LVD terminator to the end of the cable instead of using a device to terminate the bus as was commonly done with S.E. SCSI. The big advantage to LVD is that you can have a high speed SCSI bus up to 12 meters in length!

You can find those answers and many more concerning SCSI right here

I wouldn't suggest to buy a SCA-drive, I have one and they can be a PITA cause the adapters easily get lose.
The adapter seems OK by looking at the stats. You will also need an active terminator at the end of your 68-pin UW cable or an UW drive which offers termination, you can't use the Seagate drive at the end since it is an LVD drive and thus doesn't offer termination.
You can use it without any problems on your UW-channel.

Jester · Post by **Jester** » Wed Jan 08, 2003 1:57 pm

So even though it doesn't say LVD anywhere in the drive specs it is still LVD?

Absolut Talent · Post by **Absolut Talent** » Wed Jan 08, 2003 2:15 pm

quick question

do you really notice a difference in speed? honestly?

I got a seagate barracuda which runs at 7200rpms. Do you really notice the extra 2800 rpms?

Jester · Post by **Jester** » Wed Jan 08, 2003 4:49 pm

Transfer rates aren't that important to me. The main reason I'm switching is the 5.2ms seek time and the ability to actually multitask. Most new IDE drives have 9ms seek time.

DocSilly · Post by **DocSilly** » Wed Jan 08, 2003 5:50 pm

The Cheetah 18XL is U160 standard. LVD is from U2W (80MB/s) and up (U160, U320). Enjoy your new drive (even though it's a lil slow compared to my aging Cheetah X15 .... me wants X15.3, yeah baby)

Jester · Post by **Jester** » Wed Jan 08, 2003 9:32 pm

Alright. Thanks for the info Doc! Hopefully everything goes well.

Jester · Post by **Jester** » Wed Feb 19, 2003 3:58 am

Well I finally got my drive installed. Got Win2k installed on it and it's VERY nice. A lot quieter than my old IBM drive and the speed difference is quite noticable. Have one problem though.

A friend of mine gave me a 68-pin UW cable with a passive terminator and an Adaptec U160 SCSI card which I'm currently using. This card tells me the transfer rate that each device is operating under. With the original Bios that came on the card it would clock the HD at 40mb/sec. I decided to upgrade the bios to the latest so I could hopefully try and get the rated 160, however now it runs in 20mb/sec mode, and I've definitely noticed a speed difference. Any ideas on what I might do to get it above 40mb/sec? I'm downgrading the bios to the older version for now but would like to at least get LVD mode if possible.

The cable my friend gave me is about 6ft long, has 7 heads. The drive is plugged into the first head from the adapter, the terminator is plugged into the last head on the cable.

DocSilly · Post by **DocSilly** » Wed Feb 19, 2003 7:59 am

A friend of mine gave me a 68-pin UW cable with a passive terminator and an Adaptec U160 SCSI card which I'm currently using.

The cable is one big problem, it's only UW (40MB/s) with a passive terminator. You will need a LVD cable with an active LVD terminator to use the HDD at the LVD channel with full speed.
You can still use it with the UW cable on the UW channel, the transfer rate for this drive goes from 27-40MB/s, which happens to be max UW speed. Either leave it at the UW connector, which won't really harm performance, or get a LVD cable+LVD terminator for the max burst rate of U160 to use on the LVD channel, something that won't show any huge speedincrease ... especially in a single-hdd situation.

I decided to upgrade the bios to the latest so I could hopefully try and get the rated 160, however now it runs in 20mb/sec mode, and I've definitely noticed a speed difference.

I can only guess here, but I think upgrading the BIOS set the speeds to a default low setting. I assume the UW cable is at the UW channel and not the LVD. Just go into your SCSI BIOS and look around, it should somewhere display all SCSI IDs with the set speeds where you're able to change the max transfer rates.

Executioner · Post by **Executioner** » Wed Feb 19, 2003 1:47 pm

Originally posted by Absolut Talent
quick question

do you really notice a difference in speed? honestly?

I got a seagate barracuda which runs at 7200rpms. Do you really notice the extra 2800 rpms?

I have a half-bread pc - my HD is IDE, but my 2 CDROM's are SCSI. Having both, I can tell you that SCSI CDROM's are much better and smoother than IDE. On my test bed pc which as a SCSI hard drive that will burst at 80mb/sec, I really don't see that much difference between it and my 40gig Maxtor 7200 on the same system, but my SCSI HD is old compared to todays standards.

Floater · Post by **Floater** » Wed Feb 19, 2003 2:28 pm

executioner-
i have a similar setup now... an ide WD harddrive and two plextor cd-rom/rw drives. im surprised to see that you think the performance is better... i am fed up with the trouble ive had with my adaptec 2930 controller. boot time is doubled with a scsi adapter and the spin-up times for my cd-roms is just long enough to make it very annoying, even in low-level apps like windows explorer.

Executioner · Post by **Executioner** » Wed Feb 19, 2003 6:57 pm

Originally posted by Floater
executioner-
i have a similar setup now... an ide WD harddrive and two plextor cd-rom/rw drives. im surprised to see that you think the performance is better... i am fed up with the trouble ive had with my adaptec 2930 controller. boot time is doubled with a scsi adapter and the spin-up times for my cd-roms is just long enough to make it very annoying, even in low-level apps like windows explorer.

LOL, I have 2 Plextors also - a 12/4/32 burner and a 32x reader. I have them connected to a Adaptec 50 pin controller (sorry but I don't remember the model).

The reason the boot time is longer because you probaby have not turned off the channels you are not using; therefore, the card will scan the entire SCSI bus to find devices. I really don't mind the extra 5-6 seconds it takes to initialize.

DocSilly · Post by **DocSilly** » Wed Feb 19, 2003 7:09 pm

I don't mind the longer bootup time ... I rarely reboot (current uptime 2 weeks).
The spinup times for cdroms shouldn't be influenced from the interface. They depend on the speed of the drive itself, the faster they are the longer they normally take to to spin up. So a 48x IDE cdrom takes as long as the 48x SCSI cdrom to spin up.

Jester · Post by **Jester** » Wed Feb 19, 2003 8:58 pm

I figured out why it was only running in 20mb/sec mode. When I updated the BIOS I had to remove all the cables from the controller. One of the pins on the 68 pin cable was already slightly bent and it decided to not go into the hole. Surprisingly it was easy to push in with the pin getting bent. I straightened it and it's now running happily in 40mb/sec again.

For now 40mb/sec will be fine with me. Unless someone wants to sell me an LVD cable and terminator for cheap.

Bootup time is seriously dependant on the SCSI controller. With my old IWill controller it would take about 10-15 seconds for it to scan the bus. With the new Adaptec scanning all 15 channels it takes about 5 seconds. I can wait.

BTW, I thought I'd mention this drive is VERY quiet, especially for a 10k rpm drive. With all the fans in my case I can't even hear it. It also runs cool. Right now it has no active cooling and gets just a little bit warmer than my IDE drive. I"m happy.