Date: Mon, 27 Jun 2005 08:37:54 +0200 From: Martin Nilsson <martin@gneto.com> To: Artem Kuchin <matrix@itlegion.ru> Cc: freebsd-stable@freebsd.org Subject: Re: SATA vs SCSI ... Message-ID: <42BF9EC2.1060203@gneto.com> In-Reply-To: <004201c57adf$49367ad0$0c00a8c0@artem> References: <20050626233114.G57847@ganymede.hub.org> <004201c57adf$49367ad0$0c00a8c0@artem>
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Artem Kuchin wrote: > Marc G. Fournier <scrappy@hub.org> wrote: > > For the last 6 month i really think that if you don't need something > high-end scsi then you should go for SATA. Fair enough if you don't need high-end yoy shuld go lowend. But read on.. > There are test on sites such as > Tom's hardware guide and ixbt.com. They show then on sequrncial read > there is no difference between scsi and sata. That is a well known fact. It is also a totally useless parameter for server use. > Acatuallty, modern hdds use the same mechanics for sata and scsi > versions of them. The brains This is simply not true. There were a couple of drives about 10yrs ago where this was true eg. Quantum Lightning which were available in both IDE and SCSI Todays SCSI drives have _nothing_ in common with SATA/ATA drives. > However, when it comes to random read/writesscsi wins because of > command queueing. And faster accesstime and higher rotational speed (lower latency) you simply can't compare a 7200rpm drive to a 15000rpm drive no matter what interface it has. > Recently SATA with NCQ became widly available. Test show that some of those > SATA disks with NCW ***WIN*** over scsi 320. To use NCQ drive, controller and OS needs to support it, only a few controllers supports NCQ and FreeBSD have no support at all! > The test envolve artificialy randomread/write tests as well as > real application benchmarking. I din't rememeber where > excatly i saw the tests on those site, but you could search. The tests on tomshardware are windows single user centric, they never test server workloads, their audience are kids who plays games... > So, my opinion, workstation never needs SCSI and every server MUST be on > mirror or RAID5 and there you should use SATA with NCQ drivers unless, > your applicaton is really weird and needs something extremely speedy. > Then, however, > you could go for RAID 0+1 and get perfomance that SCSI will never get you. Want something cheap with lots of space? SATA Want something that works and is fast? SCSI Using SATA for databases and mailservers is going to give you bad performance. Regards, Martin -- Martin Nilsson, CTO & Founder, Mullet Scandinavia AB, Malmö, SWEDEN E-mail: martin@mullet.se, Phone: +46-(0)708-606170, Web: www.mullet.se Our business is well engineered servers optimised for FreeBSD & Linux
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