[Info-vax] Databases versus RMS

[Arne Vajhøj]

On 4/17/2012 3:40 PM, JF Mezei wrote:
> Jan-Erik Soderholm wrote:
>
>> One DBMS is not like every other DMBS. I have have had a Rdb database
>> "break" due to a simple power failure.
>
> Are there options which make a database more robust, but many database
> admins, being too inexperienced, don't think about them ?

Usually the default setup is good enough to lose data.

>                                                          or are some
> database systems, being "free/opensourced" just too easy to get majorly
> screwed up because of a power failure ?

Opn source and close source database use the same techniques.

> I am moving an RMS/All-in-1 application over to my mac using mysql, PHP
> and HTML. And it appears one can set up a mysql datbaase without any
> locking, and some of the indexing seems very primitive (there are
> different indexing engines).

MySQL has locking.

And its indexing are very standard.

I guess that you are talking about the different database
engines.

You should go for InnoDB engine.

It is also default in latest MySQL versions.

> I can understand one or two records being corrupt because an update was
> only half written,  but should that prevent the rest of the database
> from running ?

It should not.

>> And, generaly speaking, Rdb is more "safe" then a plain RMS
>> based "database".
>
> An RMS write tends to result in an immediate physical write to disk.
> (unless hidden by a storage array which delays writes).

RMS has buffering options as well.

> The reason I am askig is to know whether the "industry" has accepted
> those risks of hiding physical disks behind storage arrays that may not
> write right away and behind database engines that not only delay writes
> and cache stuff on their own, but can also get corrupt because of a
> power failure.

You can get RAID controllers with huge caches, but those comes
with battery backup.

So those should be pretty well protected against power
failure.

Arne