SCSI question

[Darknyt]

I have a PC that is ALL SCSI...Just sits there for games (Wasting away I know, but not a bad purchase for my first PC. I built it myself in 1999 and have evolved it since). Anyway...the old 8GB 7200 RPM IBM SCSI HDD and the 36 GB IBM SCSI HDD are on an adaptec 2940UW Pro controller. Will I get better throughput if I were to use an LSI u160 controlleror do I need U160 HDD as well? Would my max theoretical throughput be increased from 40MBps to 160 MBps?? Thanks....also, I am thinking of stealing all my sisters SCSI devices and replacing them with a SATA HDD (already using the Abit NF7-S) and a DVD+RW drive....Why not she doesnt use SCSI.....lol

[Peter M]

Your theoretical throughput has never been 40 MB/s either. This is the interface speed, the ceiling of what all drives together could achieve. Check what interface speeds your individual drives support, then post that back here for recommendations on controller cards.

Typically (assuming you don't have a server grade mainboard with 64-bit PCI slots there), with a mix of old and new drives you'll be best off with a Tekram 390U3W kit. This gives you two truly independent SCSI channels - one legacy UW/U for everything that has UW or slower interfaces, and a fast U160 channel for your newer drives with U2W or faster interfaces.

Alternatively you can keep the Adaptec and gather the slow stuff there, and add the LSI U160. The latter uses the same chip as the Tekram card, only in single-channel 33 MHz PCI version rather than dual channel 66 MHz PCI capable.

[zepper]

Yeah if both your drives are SE, then a U160 adapter won't do 'em much good. You need to see if the total maximum real transfer speed of your drives is above 40MB/s. If the total is substantially higher, then the LSI might show a slight improvement. To get the most out of the LSI, you would need all your drives to be LVD.
.bh.

[Darknyt]

According to IBM, my 9GB drive is LVD Fast-40...which has transfer of 80Mbytes/sec and the 36.9 GB drive is an ultra3 drive which is of course 160MB/sec transfer....Man!!!! I never realized this until now, I have been killing the max performance of my drives by using this 2940UW Pro card havent I??? Still think im bettef off with the Tekram 390U3W, only for both??? Thanks

The 9GB and the 36.9GB drives are LVD/SE, according to the tech specs on the drives themselves.

[Peter M]

When they're all LVD, meaning they're at least U2W, then moving them to an LSI U160 will do good. The Tekram card's 2nd channel is useful if you have even older, non-LVD, so called Single-Ended SCSI gear. But then you got a Single-Ended SCSI channel right there on your old Adaptec, so there's really no point in getting the Tekram over the LSI, unless you're short on PCI slots of course.

Please mind that you'll also need LVD compliant cabling and termination. Standard flat ribbon cable as probably shipped with that Adaptec won't do.

[Darknyt]

Thanks for the info, I will look into getting an LSI card next week. My standard flat ribbon went south a long time ago and I ended up replacing it with a rounded 68-pin cable almost 2 years ago(needed the airflow). Need to check to see if that cable will do me, I hope so. Thanks for all your advise guys. Always dependable, always Techimo!!!

[zepper]

Darknyt,
Those transfer rates you mentioned above aren't the real capability of those drives. They are the maximum capacity of the buses that they were designed for.
. The real maximum transfer rate of the very best U320 15k drives barely touches 80MB/sec. - takes at least FOUR of 'em (and a hefty billfold ) running flat out to saturate the bus on a good U-320 card (two on a U-160)... Comprendez vous?

Here are some SCSI vendors in case your round cable isn't LVD rated. One of these has an excellent teflon LVD cable w/ terminator for way cheap.

hypermicro.com (may offer free ground shipping if you mention www.storagereview.com - check the SR site for the latest offer)
centrix-intl.com
pc-pitstop.com (offers PayPal as a payment option)
scsi4me.com (offers PayPal too)
and I can usually find stuff for low bucks on eBay.

.bh.

[Peter M]

If you buy the LSI card "whitebox kit" from hypermicro, you'll get a terminated cable along with it. The Tekram retail box also contains all the bits and pieces you'll ever need to attach to it internally.

By the way, rounded ribbon cables are evil. Too much crosstalk.

[sechs]

Well-made rounded LVD cables are, in fact, supperior to twisted-flat cables; the key being well-made.

While Newegg has a couple of dirt-cheap LSI Ultra160 controllers, I usually suggest that people invest in late-model Adaptec cards, such as the 29160, which can be had used for quite cheap.

[zepper]

Well if the Adaptec had performance value to justify its price (even used), maybe. But they don't.
.bh.