On Thu, 27 Jun 2002, Rick Moen wrote: > Quoting Ian C. Sison ([EMAIL PROTECTED]): > > > Bottom line? For systems which use 1 drive per bus, and have > > dedicated I/O controllers (such as raid controllers), SCSI drives have > > no advantage over IDE. > > Sorry, it's not that simple. > > Cutting and pasting from my earlier post: "hot-fix mapping out of bad > sectors automatically, scatter-gather at the hardware level, ability to > do genuine low-level reformatting right in the host adapter BIOS, [and] > more-stable standards". Also fewer IRQs consumed, and (usually) lower > CPU load.
I fail to see how these additional features are actually needed in the real world, _using_available_RAID_solutions_, such as 3ware or the SCSI-to-IDE-RAID, or FC-to-IDE-RAID boxes from Arena or Promise. > Cutting and pasting from my earlier post: "hot-fix mapping out of bad > sectors automatically, Pointless, as with RAID, you simply swap out a bad drive, and replace with a new one. > scatter-gather at the hardware level All I/O is performed by a separate RAID controller anyway, so why bother with this? > ability to > do genuine low-level reformatting right in the host adapter > BIOS For a production system, do you really need to have this feature? Why not throw away the bad drive, and shove in a new one? Maybe these features are in for SCSI based drives because they are so expensive and you need to squeeze as much lifetime out of them as possible. > more-stable standards". If the IDE standards were so unstable, and unsupported, they should not have as much acceptance as they have today? > Also fewer IRQs consumed, and (usually) The 3ware escalade only gets 1 IRQ, for a max of 8 drives, 8 IDE busses. > lower CPU load. For promise or software raid, yes scsi will have a lower CPU load. but for 3ware, that is debatable, as no benchmarks are available on this yet. > That having been said, if I wanted maximum redundant storage for my > dollar, I'd use software RAID on two, three, or four ATA drives. > If I wanted to do that with less hassle and system complication, and > higher performance, I'd eschew software RAID and use 3Ware (never > Promise) ATA RAID. Agree! 100% ! \8) > If I wanted higher hardware reliability and quality, > and lack of protocol flakiness, I'd use software RAID on SCSI drives. > Maybe using an LSI Logic SCSI chipset, e.g., on a Tekram card. They're > cheap and reliable. Your statement seems to say that a lower quality SCSI card, on SCSI disks on software RAID will work more reliably than IDE drives connected to a 3ware controller? Is this by experience or conjecture? For me, the only reason to get SCSI technology is because of the "better quality or workmanship" that goes into the production of these products. I've used SCSI drives that are running 24x7 way beyond their MTBF, and still around today. Ide drives in my experience last around 2-3years at 24x7, greater than that, you're on borrowed time... (but of course, your mileage will vary..) But given today's breakneck one-upsmanship between drive producers (and software developers' disk requirements), a drive that's 2 years old is obsolete, and will be in need of replacement anyway, so why bother with 'technology that will last'? Today's raid technology makes it simple to recover from a hard drive failure, so you just need to swap in a new inexpensive disk. So indeed, why bother with SCSI at all? _ Philippine Linux Users Group. Web site and archives at http://plug.linux.org.ph To leave: send "unsubscribe" in the body to [EMAIL PROTECTED] To subscribe to the Linux Newbies' List: send "subscribe" in the body to [EMAIL PROTECTED]
