hlshd download speeds

[RS]

From: Nick
Sent: Sunday, July 17, 2016 14:19

>There was a thing at some point with Windows where external drives
>would not have write caching enabled. Perhaps the different OS versions
>and/or different drives have ended up with different settings?

>Drive caching being off means that external drives can be unplugged with
>minimal chance of file corruption, but it gives a performance penalty.

Thanks for the suggestion.  Both devices are using the Quick removal policy,
so that is not a reason for the difference  in performance.  The 29MByte/s
and 10MByte/s write speeds were with Quick removal.

Write caching is really only appropriate for devices which are only going to
be unplugged when the machine is powered down.   I know Microsoft says you
can rely on the safely remove tool, but I don't trust it.

Both drives are formatted as FAT32.  This is necessary for compatibility
with my satellite receiver, but it is also necessary for safe hot removal.
I don't know about Windows 7 and 10, but in XP and Vista Microsoft assumed
that all NTFS devices were permanently installed, so that data could be
temporarily shared between drives.  The only safe way to remove a NTFS drive
is to shut down.  I once lost 5GByte of data from a flash drive I had
formatted as NTFS.

A new bug seems to have been introduced in Windows 10.  The first time a
removable drive is use the safe removal tool keeps insisting that it is
still in use.   There is no problem on subsequent uses.  It may be that the
driver installer does not release it.

After writing the above I thought I ought at least to try write caching to 
see what effect it had.  The performance of the two drives was much more 
similar.  The Samsung drive started at 79GByte/s.  It then fell to 30GByte/s 
after about 500MByte and remained at that level.  The Maxtor drive started 
at 77GByte/s and also fell to 30GByte/s after about 500MByte.  In other 
words drive caching is only of benefit for transfers up to 500MByte, and for 
a sound drive the performance for larger transfers is similar to that 
without drive caching.  In both cases there were no dips in speed between 
files as there had been without drive caching.  With drive caching the 
Maxtor drive was able to download HLSHD at full speed.

I remain of the view that the Maxtor drive is faulty.  There should not be 
such a large deterioration in performance without drive caching.  The drive 
did not work at all with the supplied cable when it arrived.  It did work 
with a cable from another drive.