Date: Mon, 27 Jun 2005 09:19:18 +0600 From: "Sergey N. Voronkov" <serg@tmn.ru> To: "Marc G. Fournier" <scrappy@hub.org> Cc: freebsd-stable@freebsd.org Subject: Re: SATA vs SCSI ... Message-ID: <20050627031918.GA20199@tmn.ru> In-Reply-To: <20050626233114.G57847@ganymede.hub.org> References: <20050626233114.G57847@ganymede.hub.org>
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On Sun, Jun 26, 2005 at 11:34:22PM -0300, Marc G. Fournier wrote: > > looking at the specs between two cards, the SATA card(s) seem to rate > ~100-150MB/s on each channel (if I'm reading right), with both the 3Ware > and ICP cards having 4 individual channels ... looking at the SCSI cards, > they are rated at 320MB/s, but that is total for the SCSI bus itself, > right? It is dependant of the card too. You can get a 3 channel Ultra320 card for 3 drive RAID 5... > So, if I have three drives on a SCSI bus, each 'maxing out evenly', I'd > be cap'd at about the same 100MB/s per drive, no? > > In fact, looking at the SATA 2.x specs, each chanell there is rated at > 300MB/s, which, again, if I could 'max out evenly', could seriously blow > away the SCSI bus itself ... That is a theory... > *If* I'm reading this right ... ? And now from my practice: 1) You CAN'T get maximal throuput from 150/160 MB/s bus - the is no such drives today at the market. 2) Avg. seek and access time of 7200 SATA drives are FAR BELOW such of old Seagate Cheetah/Maxtor Athlas 10K. So is a situation with a WD Raptor 10K SATA too - they are SLOWER! (I'm not shure why, but from my test: 2xPIII-1.4/1G RAM/2x36G Cheeta 10K in RAID 1 (AMR Express; One U160 channel) ws. 2xXeon 3.0/2G RAM/2x72G Raptor in RAID 1 (Intel SRCS16; Separate SATA-150 channel for each drive) Ports three checkout is about 20% faster on the first comp. As an result: If you need to have FAST disk subsystem - buy SCSI. If you need large storage or you don't want to pay to much money - buy SATA. Best Ragards, Serg N. Voronkov, Sibitex JSC.
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