On 09/23/2014 11:20 AM, Roberto Ragusa wrote:
On 09/23/2014 03:28 AM, jd1008 wrote:
Have an external drive, wd20npvx , 2 tb.
It spinsx@7200rpms, and is touted to have 600 gigabit/s
on the wire speed. However, fc20 always connects it as
having dma100, when the esata port supports 300 gigabits/s
So, what's with Fedora to limit it to dma100?
To wit:
[ 3571.062358] ata11: SATA link up 3.0 Gbps (SStatus 123 SControl 0)
.
.
.
[ 3571.063587] ata11.00: ATA-9: WDC WD20NPVX-00EA4T0, 01.01A01, max UDMA/133
.
.
[ 3571.065292] ata11.00: configured for UDMA/100
You are confusing numbers. Forget about 600gigabits/s.
SATA is 1.5Gpbs or 3.0Gbps or 6.0Gbps.
Your drive link is working at 3.0Gbps, probably because you do not
have a 6.0Gbps controller.
(bps is bit per seconds, you have to divide by 10 to obtain bytes
per second, 150MB/s, 300MB/s, 600MB/s)
PATA had a lot of different transfer mode, the best of them were
the UDMA/100 (100MBps) or, more rarely, UDMA/133 (133MBps).
(Bps is bytes per second, 100MB/s, 133MB/s)
AFAIK, UDMA values are often printed in SATA logs, with no real
meaning at all.
I do know that if the sata controller operates at 3g bits/s, then the
on-the-wire
speeds of transfer to/from computer/disk will be 3g bits/s.
If the UDMA values in the log
So, how can I ascertain if I am getting much better transfer (read/write)
speeds without doing io from one unmounted partition of drive A to an
unmounted
partition on disk B?
Usually I use dd with bs=512M or 256M (in case I have a lot of programs
running).
I have seen 65 mbytes/s, but that is achievable even with UDMA133 PATA
drives spinning
at 7200rpm.
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