Steve Polyack wrote: > On 2/10/2010 12:02 AM, Dan Langille wrote: >> Don't use a port multiplier and this goes away. I was hoping to avoid >> a PM and using something like the Syba PCI Express SATA II 4 x Ports >> RAID Controller seems to be the best solution so far. >> >> http://www.amazon.com/Syba-Express-Ports-Controller-SY-PEX40008/dp/B002R0DZWQ/ref=sr_1_22?ie=UTF8&s=electronics&qid=1258452902&sr=1-22 > > Dan, I can personally vouch for these cards under FreeBSD. We have 3 of > them in one system, with almost every port connected to a port > multiplier (SiI5xxx PMs). Using the siis(4) driver on 8.0-RELEASE > provides very good performance, and supports both NCQ and FIS-based > switching (an essential for decent port-multiplier performance). > > One thing to consider, however, is that the card is only single-lane > PCI-Express. The bandwidth available is only 2.5Gb/s (~312MB/sec, > slightly less than that of the SATA-2 link spec), so if you have 4 > high-performance drives connected, you may hit a bottleneck at the > bus. I'd be particularly interested if anyone can find any similar > Silicon Image SATA controllers with a PCI-E 4x or 8x interface ;)
Here is SiI3124 based card with built-in PCIe x8 bridge: http://www.addonics.com/products/host_controller/adsa3gpx8-4em.asp It is not so cheap, but with 12 disks connected via 4 Port Multipliers it can give up to 1GB/s (4x250MB/s) of bandwidth. Cheaper PCIe x1 version mentioned above gave me up to 200MB/s, that is maximum of what I've seen from PCIe 1.0 x1 controllers. Looking on NCQ and FBS support it can be enough for many real-world applications, that don't need so high linear speeds, but have many concurrent I/Os. -- Alexander Motin _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
