Date: Wed, 25 Feb 2009 21:58:04 -0600 From: Josh Paetzel <josh@tcbug.org> To: questions@freebsd.org Subject: SAS drives seem slow Message-ID: <F1AB5657-660C-4554-BCF5-9E5C8001C74D@tcbug.org>
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I have a 3ware 9690SA SAS RAID controller in a PCI-e 8x slot with Fujitsu MBA series 15k SAS drives attached, and the array is coming up as: da0 at twa0 bus 0 target 0 lun 0 da0: <AMCC 9690SA-4I DISK 4.06> Fixed Direct Access SCSI-5 device da0: 100.000MB/s transfers da0: 138272MB (283181056 512 byte sectors: 255H 63S/T 17627C) The controller is probed as: twa0: <3ware 9000 series Storage Controller> port 0x2000-0x20ff mem 0xe0000000-0xe1ffffff,0xe4100000-0xe4100fff irq 16 at device 0.0 on pci2 twa0: [ITHREAD] twa0: INFO: (0x15: 0x1300): Controller details:: Model 9690SA-4I, 128 ports, Firmware FH9X 4.06.00.004, BIOS BE9X 4.05.00.015 FreeBSD services.tcbug.org 8.0-CURRENT FreeBSD 8.0-CURRENT #0: Mon Feb 16 21:07:14 UTC 2009 root@:/usr/obj/usr/src/sys/SERVICES amd64 But 6.x and 7.x give similar results. The disks themselves are capable of sequential read/write in the 180 Meg/sec range, so I'm trying to understand why I'm being told they are 100 Meg/sec, and why that seems to be their real world performance cap. # dd if=/dev/zero of=stuff bs=8m count=100 100+0 records in 100+0 records out 838860800 bytes transferred in 8.711125 secs (96297644 bytes/sec) Thanks, Josh Paetzel
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