[Info-vax] Databases versus RMS

[Johnny Billquist]

On 2012-04-18 20:53, Jan-Erik Soderholm wrote:
> Johnny Billquist wrote 2012-04-18 19:53:
>> On 2012-04-18 15:43, Bob Koehler wrote:
>>> In article<jmm94e$atj$1 at Iltempo.Update.UU.SE>, Johnny
>>> Billquist<bqt at softjar.se> writes:
>>>>
>>>> Even beyond any language issue, or RMS details, the OS can cache and
>>>> defer actual writes to the disk without you ever knowing about it. Not
>>>> to mention that disks also cache things...
>>>>
>>>
>>> OS cache? Are you dreaming UNIX? VMS has never cahced any data I
>>> cared about without my explicitly telling it to do so.
>>
>> Really? I find it hard to believe. RSX have done caching of things
>> from the
>> disk at that low level since day one. F11ACP do some caching for the
>> system, keeping the most recently referenced directories around in a
>> cache
>> in the ACP.
>>
>> Newer versions of RSX also do caching of individual blocks fully
>> transparent at the OS level. It's selectable if you want writes to be
>> write-back or write-through.
>>
>> That VMS would have none of this sounds unlikely, as well as very bad for
>> performance.
>>
>>> Disks that cache should use a non-volatile memory to do so, or
>>> contain internal power storage sufficient to flush the cache.
>>
>> Right. But that is still a cache that can cause surprising results,
>> although I freely admit that the caches in the disks are normally very
>> reliable.
>>
>> Johnny
>>
>
> You are mixing read and write cache. Make sure you are talking
> about the same thing before arguing... :-)

Huh? They are not separate! If they were, you'd get some really bad results.

But even disregarding that, I do not understand what you were 
commenting. Please explain.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol