[Info-vax] naming convention in VMS MAIL

[Arne Vajhøj]

On 12/19/2018 8:43 PM, Dave Froble wrote:
> 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.
> 
> 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.

Probably so.

But there are always exceptions.

Arne