SATA/SAS link speed negotiation

Peter Hamilton <peterghamilton@xxxxxxxxx> · Thu, 14 Jul 2011 10:23:05 -0600

I'm trying to find out what the negotiated speed is on a SATA port.  dmesg reports the negotiated speed, but I'm hoping to find it somewhere in /sys or /proc (or some other tool).  Scraping dmesg is a messy process as I'm starting with a block device.  I would have to trace the block device to the scsi address and translate that to an ata address.

Here's the scsi and block device info from dmesg:

scsi 7:0:0:0: Direct-Access     ATA      WDC WD1600AAJS-2 01.0 PQ: 0 ANSI: 5
sd 7:0:0:0: [sdd] 312581808 512-byte logical blocks: (160 GB/149 GiB)
sd 7:0:0:0: [sdd] Write Protect is off
sd 7:0:0:0: [sdd] Mode Sense: 00 3a 00 00
sd 7:0:0:0: [sdd] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
sd 7:0:0:0: [sdd] Attached SCSI disk
sd 7:0:0:0: Attached scsi generic sg3 type 0

Here's the corresponding ata info from dmesg:

ata7: SATA link up 3.0 Gbps (SStatus 123 SControl 370)
ata7.00: ATA-8: WDC WD1600AAJS-22L7A0, 01.03E01, max UDMA/133
ata7.00: 312581808 sectors, multi 0: LBA48 NCQ (depth 31/32), AA
ata7.00: configured for UDMA/133

Finding the SATA link speed in dmesg would be much cleaner than scraping dmesg.  Does anyone know where I might find that?

Also, for a SAS HBA, the link speed is not reported to dmesg.  Does anyone know how to find the link speed for a SAS drive?

Thanks,

Peter
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