[Info-vax] MIPS vs. VUPS

[Paul Sture]

On 2015-07-27, Bob Gezelter <gezelter at rlgsc.com> wrote:
> On Monday, July 27, 2015 at 5:04:45 AM UTC-4, Paul Sture wrote:

>> Gzipping the uncompressed files takes ~50 minutes on my Mac mini (and 24
>> minutes to decompress), which isn't a trivial operation either, and I'm
>> simply not that desperate for the disk space saved in this instance
>> (83GB comes down to 23GB).  On the bandwith front, I can certainly ship
>> the uncompressed files to another system faster than going through the
>> compression.
>> 
>> Folks seem to get excited about compression at the file systems level
>> too, but when the majority of files involved with a typical office
>> file server are already compressed (.docx, .xlsx, jpg, mp3/4 etc)
>> trying to compress them further might just be a waste of time.
>> 
>
> Compression is a tradeoff between processing power and some other
> resource. With compression, the content of the data has a large
> influence. Data containing many repeating strings (e.g., blanks,
> zeroes, or printable ASCII) can yield very substantial compressions
> (e.g., I have seen very much more than two orders of magnitude) over
> uncompressed data. If the data is random, encrypted, or previously
> compressed, the gains are negligible for significant processing.

Indeed, the example I quoted above was 83GB coming down to 23GB. Some
50GB of the original is a SimH instance with a full installation or two
of VMS plus the Freeware CDs.  On another note, for backup purposes that
combination of data dedups extremely well :-)

> With a high bandwidth link and low-compression yield, compression is
> indeed not a gain. 

It's been an interesting learning curve here.  What I have is a server
with relatively low CPU power, but a disk system which is super fast
compared to the Mac.  It's now running SmartOS rather than Suse and that
brings ZFS, zones, and the OS loaded into RAM.

ZFS: amongst a whole pile of other goodies, ZFS shares read requests
among mirror set members - c.f. the VMS ability HBVS ability to
balance reads across shadow members.

zones: although what you are running looks like a virtual machine, and
has its own sandboxed environment like a virtual machine, its processes
are running on the host.  Linux or Windows via KVM are also supported,
and for selected Linux distributions there's another flavour known as
LX, designed to replace KVM; it does this by intercepting Linux system
calls.

OS in RAM: Not just the OS but all installed software.  Combined with
ZFS atop faster disks, getting to a Python prompt or compiling
small to medium sized* programs is faster than on my Mac.

* being deliberately vague here; I've yet to compare the compile times
of large complex programs

-- 
 If it jams - force it. If it breaks, it needed replacing anyway.