Ok - I take it back - I'm reading through this now, and realising that the reviews are pretty clueless in several places...
On Apr 6, 2005 8:12 PM, Alex Turner <[EMAIL PROTECTED]> wrote: > Ok - so I found this fairly good online review of various SATA cards > out there, with 3ware not doing too hot on RAID 5, but ok on RAID 10. > > http://www.tweakers.net/reviews/557/ > > Very interesting stuff. > > Alex Turner > netEconomist > > On Apr 6, 2005 7:32 PM, Alex Turner <[EMAIL PROTECTED]> wrote: > > I guess I'm setting myself up here, and I'm really not being ignorant, > > but can someone explain exactly how is SCSI is supposed to better than > > SATA? > > > > Both systems use drives with platters. Each drive can physically only > > read one thing at a time. > > > > SATA gives each drive it's own channel, but you have to share in SCSI. > > A SATA controller typicaly can do 3Gb/sec (384MB/sec) per drive, but > > SCSI can only do 320MB/sec across the entire array. > > > > What am I missing here? > > > > Alex Turner > > netEconomist > > > > On Apr 6, 2005 5:41 PM, Jim C. Nasby <[EMAIL PROTECTED]> wrote: > > > Sorry if I'm pointing out the obvious here, but it seems worth > > > mentioning. AFAIK all 3ware controllers are setup so that each SATA > > > drive gets it's own SATA bus. My understanding is that by and large, > > > SATA still suffers from a general inability to have multiple outstanding > > > commands on the bus at once, unlike SCSI. Therefore, to get good > > > performance out of SATA you need to have a seperate bus for each drive. > > > Theoretically, it shouldn't really matter that it's SATA over ATA, other > > > than I certainly wouldn't want to try and cram 8 ATA cables into a > > > machine... > > > > > > Incidentally, when we were investigating storage options at a previous > > > job we talked to someone who deals with RS/6000 storage. He had a bunch > > > of info about their serial controller protocol (which I can't think of > > > the name of) vs SCSI. SCSI had a lot more overhead, so you could end up > > > saturating even a 160MB SCSI bus with only 2 or 3 drives. > > > > > > People are finally realizing how important bandwidth has become in > > > modern machines. Memory bandwidth is why RS/6000 was (and maybe still > > > is) cleaning Sun's clock, and it's why the Opteron blows Itaniums out of > > > the water. Likewise it's why SCSI is so much better than IDE (unless you > > > just give each drive it's own dedicated bandwidth). > > > -- > > > Jim C. Nasby, Database Consultant [EMAIL PROTECTED] > > > Give your computer some brain candy! www.distributed.net Team #1828 > > > > > > Windows: "Where do you want to go today?" > > > Linux: "Where do you want to go tomorrow?" > > > FreeBSD: "Are you guys coming, or what?" > > > > > > ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
