FuzzButt Posted June 30, 2003 Share Posted June 30, 2003 Just a quick question for those fimilar with server type drives. Is anyone else having issues purchasing 9GB 10,000 RPM LVD SCSI drives? We use HP branded 9GB drives in our HP LHII Netservers and are having a hard time replenishing our stock of them. I know there are 18GB drives out there but for some reason our unix people need 9GB. I guess the lower capacity drives are starting to become harder to find. Chris Quote Link to comment Share on other sites More sharing options...
Eric Legge Posted July 6, 2003 Share Posted July 6, 2003 Am I missing information here?Surely you could buy bigger drives and then partition them to the size of drive you require for Unix.Eric,http://www.legge40.freeserve.co.uk/BuyerBeware.htm Quote Link to comment Share on other sites More sharing options...
RandomBox Posted July 13, 2003 Share Posted July 13, 2003 Just recently I saw an online ad for a 38GB 10,000rpm U160SCSI HDD for under $150!I think (IMHO) that queuing up multiple (smaller) drives on a SCSI chain, will reduce your thruput; instead of attaching a single SCSI HDD of bigger size! For example (me thinx), having TWO 9GB HDD on a U160 Adapter will halve the thruput speed >> in comparison to a SINGLE 18G HDD!Please correct me on this IMHO, if I am in error! Quote Link to comment Share on other sites More sharing options...
Peachy Posted July 14, 2003 Share Posted July 14, 2003 Just recently I saw an online ad for a 38GB 10,000rpm U160SCSI HDD for under $150!I think (IMHO) that queuing up multiple (smaller) drives on a SCSI chain, will reduce your thruput; instead of attaching a single SCSI HDD of bigger size! For example (me thinx), having TWO 9GB HDD on a U160 Adapter will halve the thruput speed >> in comparison to a SINGLE 18G HDD!Please correct me on this IMHO, if I am in error!Sorry RandomBox,That's not quite true. The theoretical throughput rate of a SCSI bus is the maximum transfer rate that the bus can perform and no SCSI hard disk on this planet will ever reach that upper limit by itself. An Ultra160 SCSI bus has a maximum bus speed of 160 MB/s, but if its not using a 64-bit PCI bus then it will max out at 133 MB/s, or more realistically at 100 MB/s. A 10K U160 SCSI drive may get a maximum transfer rate of about 60 MB/s when you factor in all the latency, overhead and mechanical speed of the read/write heads. So, putting two SCSI drives on the same bus is not going to halve the bandwidth; they won't even reach its limit! Now, let's get to the problem where throughput might be halved. The problem lies in the signaling that the SCSI device uses on the bus. For practical sake there are two types of SCSI devices with regards to electrical signaling: the older single-ended (SE) and the newer low-voltage differential (LVD). SE devices have a maximum SCSI throughput of 20 MB/s. Anything faster requires LVD. If you place a SE device on the same bus as a LVD device, the LVD device will only reach a maximum bandwidth of 20 MB/s otherwise the SE device will for all intents and purposes, be fried. Now, most modern SCSI controllers have at least 2 independent buses, and some have even 3. This would allow you to put LVD and SE devices on different buses on the same controller and each device would then operate at their rate speeds.My only experience with SCSI hard drives was with SCSI-2 and FastSCSI Quantum drives in a 486 and later a Pentium 120. A SCSI-2 drive (10 MB/s max throughput) on a 486 made life with Windows 3.1 and Windows 95 infinitely more enjoyable than with PIO3 ATA drives maxing out at 3 MB/s!!! I still have that 1.2 GB Quantum SCSI-2 drive and every once in awhile I use it to quickly test something and it shows its age. The same system but with an ATA/33 drive much more responsive and fast compared to the SCSI setup. But, cost has kept me (or more precisely, bang for the buck value) from buying an LVD SCSI drive to use with my Adaptec 19160 SCSI controller. Its bandwidth is being wasted by a Plextor SCSI-2 CD-R and a Seagate Travan-4 tape drive. Quote Link to comment Share on other sites More sharing options...
RandomBox Posted July 14, 2003 Share Posted July 14, 2003 Thanx Peachy,I could either sit or stand corrected >> your option! Adaptec #39160 provides for two separate busses! "A" channel can be employed for slower (SCSI-2 legacy) devices and "B" channel for the real U160 devices with no speed penalty!But may still break your bank account! Adaptec #39160 is now considered an old hardware as the U320 has been out for quite sometime! It maybe worth to search EBay for it, if interested! Quote Link to comment Share on other sites More sharing options...
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