8.0-RELEASE/amd64 - full ZFS install - low read and write disk performance

Alexander Motin mav at FreeBSD.org
Sun Jan 24 21:54:43 UTC 2010

Dan Naumov wrote:
> This works out to 1GB in 36,2 seconds / 28,2mb/s in the first test and
> 4GB in 143.8 seconds / 28,4mb/s and somewhat consistent with the
> bonnie results. It also sadly seems to confirm the very slow speed :(
> The disks are attached to a 4-port Sil3124 controller and again, my
> Windows benchmarks showing 65mb/s+ were done on exact same machine,
> with same disks attached to the same controller. Only difference was
> that in Windows the disks weren't in a mirror configuration but were
> tested individually. I do understand that a mirror setup offers
> roughly the same write speed as individual disk, while the read speed
> usually varies from "equal to individual disk speed" to "nearly the
> throughput of both disks combined" depending on the implementation,
> but there is no obvious reason I am seeing why my setup offers both
> read and write speeds roughly 1/3 to 1/2 of what the individual disks
> are capable of. Dmesg shows:
> atapci0: <SiI 3124 SATA300 controller> port 0x1000-0x100f mem
> 0x90108000-0x9010807f,0x90100000-0x90107fff irq 21 at device 0.0 on
> pci4
> ad8: 1907729MB <WDC WD20EADS-32R6B0 01.00A01> at ata4-master SATA300
> ad10: 1907729MB <WDC WD20EADS-00R6B0 01.00A01> at ata5-master SATA300

8.0-RELEASE, and especially 8-STABLE provide alternative, much more
functional driver for this controller, named siis(4). If your SiI3124
card installed into proper bus (PCI-X or PCIe x4/x8), it can be really
fast (up to 1GB/s was measured).

Alexander Motin

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