system response issue

[jd1008]

On 07/13/2015 03:13 PM, Patrick O'Callaghan wrote:
> On Mon, 2015-07-13 at 13:50 -0600, jd1008 wrote:
>> I started a tar command from
>> one external eSATA drive (ext4), connected to eSATA port,
>> out to a USB flash drive (with vfat). The USB stick is touted
>> to support 50MB/s write, 160MB/s read.
> Have you actually measured its real write speed for large files? Try
> something like:
>
> time dd if=/dev/zero of=/the/usb/drive count=1000 bs=1M
>
> You might be surprised.
>
> poc
As  I just replied with the actual read/write performance data
on this USB 3.0 SUperTalentExpress Drive (256GB), I am
much more surprised by the fact that while tarring a large
dir to it from a fast eSATA drive, the system becomes nearly
unusable!!!
So, if this "shtick" is so slow, why is writing to it killing the response
time for everything else?