Good evening,
I am a bit confused by the output of smartctl and the messages log.
sudo smartctl -a /dev/sdd states the following link speed for my hard drive:
QuoteATA Version is: ATA8-ACS T13/1699-D revision 4
SATA Version is: SATA 3.0, 6.0 Gb/s (current: 3.0 Gb/s)
while the messages log for the same drive says
Quote
ata4.01: ATA-8: ST3000VX000-1CU166, CV23, max UDMA/133
Whats correct?
There's two pieces of hardware involved where speed is concerned; the mobo SATA interface and the interface board on the drive.
Where did you retrieve the info you said is in "the messages log for the same drive"?
Interesting. I have no drive entries, in the same location, under messages.
In any case, the following may be useful:
______________________________________________________________
From one of my servers:
ata2.00: ATA-10: ST4000DM005-2DP166,0001, max UDMA/133
This came from the output of dmesg or Display message or driver message.
dmesg displays kernel hardware drivers and other specifics.
ATA Version is: ACS-3 T13/2161-D revision 5
SATA Version is: SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
This from the output of smartctl which is a direct query to the drive itself.
_______________________________________________________________
Your drive, which is a 3TB SATA drive capable of 6 Gb/s is running at 3/GBs.
If I was to hazard a guess at the reason why, maybe you might have an older motherboard..??
_______________________________________________________________
Your drive, which is a 3TB SATA drive capable of 6 Gb/s is running at 3/GBs.
If I was to hazard a guess at the reason why, maybe you might have an older motherboard..??
Ok, 3 Gbs would be great. And yes, its an older mainboard.
But I was confused, as UDMA 133 is 133 MBs, whereas 3 Gbs would be 375 MBs.
Additionally, my RAID 5 (3 drives) does not show the performance I was expecting. Its about 260 MBs - I would expect that from a UDMA 133 connection.
As my drives can transfer (read) up to 150/160 MBs (via SATA II), I would expect RAID 5 transferrates of arround 300 MBs.
Additionally, my RAID 5 (3 drives) does not show the performance I was expecting. Its about 260 MBs
If you're running 1Gb/s Ethernet, you're never going to see the I/O that's theoretically possible with RAID5 even with drives running at 3Gb/s. The "network" (1Gb/s) is a hard bottleneck . For this reason and others RAID is not, by any objective measure, good for home use. SNAPRAID is better as it offers full hard drive recovery and more, to include bitrot protection..
If you're running RAID5 I hope you have backup. (On the other hand, backup for anything you don't want to lose is a must in any case.)
If you're running 1Gb/s Ethernet, you're never going to see the I/O that's theoretically possible with RAID5 even with drives running at 3Gb/s. The "network" (1Gb/s) is a hard bottleneck .
Thats why I have a 10 Gb/s NIC insalled and a direct connection to the 10Gb/s NIC in my PC - alongside my normal 1Gb/s connection to the NAS.
So It should be possible to see the maximum RAID5 perfomance - at least I hoped so. But turned out, I am stuck with 240 MB/s - even now that I have a 4 drive RAID 5 (was 3 drive before) 
If you have dual paths, both 1Gb/s and 10Gb/s, there's a number of possibilities where the network traffic might default to the 1Gb/s connection, or the 10Gb/s connection may fall back to 1Gb/s. Further, there's a number of reasons why a Windows box might not perform up to par.
If you want to test raw I/O, try doing it through a single path, with the 10 Gb/s nics only.
If you're worried about top speed, it might be time to pop for a newer mobo where 6Gb/s is possible on SATA ports. The bandwidth is doubled. -> Transfer Rates. (As noted in this article, backward compatibility may come with a few kinks.) Also worth mentioning, with Linux, getting the latest cutting edge hardware is not a good idea. It's best to buy something that has been out for at least a year, preferably two.
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