Date: Fri, 1 Jun 2007 13:41:27 -0400 From: Martin Cracauer <cracauer@cons.org> To: Fluffles <etc@fluffles.net> Cc: Martin Cracauer <cracauer@cons.org>, freebsd-hardware@freebsd.org Subject: Re: Non-raid PCIe SATA controller with 8 ports? Message-ID: <20070601174127.GA58394@cons.org> In-Reply-To: <46603FD2.8070400@fluffles.net> References: <20070601144512.GA51002@cons.org> <46603FD2.8070400@fluffles.net>
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Fluffles wrote on Fri, Jun 01, 2007 at 05:48:34PM +0200: > >I don't need hardware RAID. I suppose I can use an 8-port Areca as a > >dumb controller, but that's kinda wastish. > > > > Well, an Areca might give you the flexibility to use true RAID and even > on single disks you can benefit from increased performance due to > request reordering and the onboard buffercache. Be aware that any > controller with write-back cache offers a potential dataloss risk, > without the use of a battery backup unit (BBU). > > Also, if you need performance, why would you want to use an Areca as a > normal controller, why not pick RAID0 or RAID5? Do you really need 8 > seperate disks? I use software raid for a variety of reasons including: - can put in disks on other controllers, such as in an emergency put a P-ATA disk as a replacement. - working SMART. - more control, no "black box". - buying one hardware raid controller is a joke from a reliability standpoint, you'd need a second one on the shelf. - freedom to move to a different controller. To my knowledge none of the hardware raid makers obey to the common disk file format, not even optionally. Neither does software raid, but software raid doesn't bind me to a piece of hardware. - as you mentioned, without the battery backup the cache on the controller would have to be write-through, which disabled much of the advantage of the thing. I found the performance with modern CPUs to be more than sufficient, even on raid-5 writes. http://cracauer-forum.cons.org/forum/raid.html The thing that I'm trying to solve is not speed as such. What goes on my nerves is that I can't have NCQ on the NVidia SATA ports, and hence have to use the disk's write cache. Also, boards with more than 4 ports usually only have 4 ports on the primary controller and the rest of the ports are on some 32bit/33MHz PCI bus piece of junk like the Promise 3112. Hence, a dumb but decent 8-port controller would give me what I want. (Well, that was when I thought we do have NCQ on ICH SATA :-/)/ Martin -- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Martin Cracauer <cracauer@cons.org> http://www.cons.org/cracauer/ FreeBSD - where you want to go, today. http://www.freebsd.org/
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