February 4, 201511 yr Hi all, I just upgraded my parity drive from 2GB to 3GB. The rest of my drives are 2GB, but the store only had 3GB 7200 SATA3 drives. This is the drive: http://www.newegg.com/Product/Product.aspx?Item=N82E16822148844 Anyway, according to the SMART page in the UI, my parity drive is "sdd", and is not running at the full 6 Gb/s: $ smartctl -a /dev/sdd | grep SATA SATA Version is: SATA 3.1, 6.0 Gb/s (current: 3.0 Gb/s) The syslog seems to confirm that I'm running slower: $ grep ata.*ST3000DM001 /var/log/syslog Feb 3 19:59:05 storage kernel: ata6.00: ATA-9: ST3000DM001-1ER166, W500ARQN, CC25, max UDMA/133 My controller is the "SuperMicro AOC-SAS2LP-MV8 PCI-Express 2.0 x8 SATA / SAS 8-Port Controller Card". I made sure I'm running the latest firmware for the controller. I checked that I don't have to set any jumpers on the drive to go full speed. I didn't update my hard drive firmware, but I could try that if folks think it would help. I have two other data drives running at 6 Gb/s, so I know the controller can do it. Any ideas? TIA!
February 4, 201511 yr This could be the cabling to the drive -- either the cable doesn't pass the 6Gb testing from the controller; or it isn't seated well (try unplugging, replugging it). Or if the drive's in a hot-swap caddy, it may not be seated well, or there may be a defect in the connector or the PCB that causes the slower speed. HOWEVER ... it really doesn't matter. 3Gb is well above the sustained transfer rate for the drive, so it will make virtually NO difference in your performance. [The only transfers that occur at interface speed are those to/from the drive's buffer -- a VERY tiny % of overall transfer activity]
February 4, 201511 yr ... you could try simply using a different cable; a different slot in the hot swap cage (if using one); or simply connecting the drive to a motherboard port.
February 4, 201511 yr Author Well, I tried swapping cables to the controller, and connecting it to my motherboard. Then I pulled the drive and attempted to upgrade its firmware on a Windows machine. It seemed to work, but the BIOS version isn't the latest one. (?) Oh well, if the parity drive's bus speed isn't the limiting factor as you say, I guess I can live with it at 3 Gb/s.
February 4, 201511 yr Trying other cables and a different controller (motherboard ports) at least show the issue is with the drive, not with your setup. But as I noted above, it simply doesn't matter => you wouldn't be able to tell the difference if it suddenly decided to work at 6Gb ... the only time it really matters with modern drives is if you're using an SSD.
February 4, 201511 yr Author I'm not sure if the controller has its own BIOS menu. Also, like I said I have 2 other drives (Toshibas) that could go at 3.0 Gb/s, but are running at 6.0 Gb/s.
July 7, 20206 yr I ran into this issue as well. It seemed to have been the port on my SATA controller. Every drive I swapped into the port experienced the limitation of connecting at 3.0 Gb/s instead of 6.0 Gb/s. Reading upward in the post I decided not to let it bother me, until I ran a parity check on the array. The parity check ran slower. I am used to seeing checks run between 130 - 140 MB/s and finish around 17 hours. with my parity drive on 3.0 Gb/s, the parity check ran between 95 - 105 MB/s and took around 22 hours. I am already a little apprehensive while running a parity check as it spins all the drives with data, but spinning them and reading slower (meaning spinning longer duration) is something my anxiety could not handle. I had an unassigned 1tb toshiba drive that i used for VMs that ran @ 3.0 Gb/s. So I just traded SATA ports. If i didnt have that little ram-in-the-bush I would probably be purchasing a larger multi-port SATA controller card
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