Question about DMA speed of eSATA 600 drives.

[jd1008]

On 09/24/2014 02:38 AM, Roberto Ragusa wrote:
> On 09/23/2014 08:31 PM, jd1008 wrote:
>> 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.
> Try
>
> hdparm -t /dev/sda    (if your drive is sda)
>
> this will do a speed test reading the first part of the disk.
>
> Consider that:
>
> - the beginning of the disk is faster then the final part (which can be about
> half speed)
>
> - normal drives have actual physical speed from 50MB/s to 200MB/s, even if
> the SATA link permits a faster speed
>
> - your drive is a "WD Green", which are generally quite slow, do not expect
> spectacular numbers
>
> Finally, if you get significantly slower numbers for /dev/sda1 with respect
> to /dev/sda, maybe your partitions are not well 4k aligned (this happens when
> the partitioning tool is too old).
>
Thanx Roberto.
It seems the 600gibit/s might be useful only for SSD drives with 1600MHz 
memory chips.
I wonder if spinning mass storage drives are seeing the approaching EOL.