[Info-vax] naming convention in VMS MAIL

[Dave Froble]

On 12/19/2018 8:35 PM, Arne Vajhøj wrote:
> On 12/19/2018 8:29 PM, Dave Froble wrote:
>> On 12/19/2018 7:36 PM, Stephen Hoffman wrote:
>>> The core OpenVMS design features are inherently slow.  SSDs have helped
>>> there as have caching controllers, but the default behavior is a write
>>> to persistent storage.  There are more than a few cases where that's
>>> less than desirable, or where it would be preferable to cache a bunch of
>>> operations and flush that data less frequently.  That's certainly
>>> possible on OpenVMS, but OpenVMS isn't good at presenting this trade-off
>>> to the developers.  There've been cases where—for instance—temporary
>>> stub files opened and written and closed frequently can utterly saturate
>>> a system.  Bad design, but other systems can keep all that in memory
>>> until flushed, so the storage I/O paths don't get hammered.  And
>>> clustering works because the data is on static storage and the OpenVMS
>>> I/O caches are usually write-through and not write-back.  Trade-offs
>>> abound here, of course.
>>
>> And some of us are rather happy with that.  When I do a write, I
>> really want to believe that the data is truly written.  One can
>> mention batteries, UPS, and such, but, that doesn't give me the same
>> warm fuzzy feeling.
>
> Yes.
>
> While it can be difficult on VMS to get enough caching to make IO fast
> then on other platforms and technologies it may be a problem how to
> disable caching to avoid the risk of data loss.
>
> Arne

We find that current HW, with decent amounts of memory used for cache, 
has quite adequate I/O performance.  But perhaps our resource demands 
are less than what some others may need.

I'm wondering if, for most users, the "I/O slowness" might be a past 
problem, but is no longer a problem.

-- 
David Froble                       Tel: 724-529-0450
Dave Froble Enterprises, Inc.      E-Mail: davef at tsoft-inc.com
DFE Ultralights, Inc.
170 Grimplin Road
Vanderbilt, PA  15486