[Info-vax] Re; Spiralog, RMS Journaling (was Re: FREESPADRIFT)

[Kerry Main]

> -----Original Message-----
> From: Info-vax [mailto:info-vax-bounces at info-vax.com] On Behalf Of
> Stephen Hoffman via Info-vax
> Sent: 18-Jun-16 3:24 PM
> To: info-vax at info-vax.com
> Cc: Stephen Hoffman <seaohveh at hoffmanlabs.invalid>
> Subject: Re: [New Info-vax] Re; Spiralog, RMS Journaling (was Re:
> FREESPADRIFT)
> 
> On 2016-06-18 18:31:49 +0000, Kerry Main said:
> 
> > One only has to power off a system in the middle of a benchmark on
> that
> > system to see what the effects could be in the real world.
> 
> I've worked more than a few OpenVMS systems that have to be
> manually
> rebooted, and with non-trivial recovery processing.  There's no APIs
> for coordinating with backups, no integrated means of checkpointing
> application data, and a whole pile of other limits.
> 
> > With new disks like SSD and really big memory technologies emerging,
> > one needs to ask whether the difference in perf is really worth  the=
> > potential for data integrity issues?  Especially when one considers the
> > considerable pain  one must go through to recover from some
> significant
> > event like a system crash or hardware error or power failure on a write
> > back designed system.
> 
> Yeah, and I've had that same issue with long-running jobs on OpenVMS,
> where the primitive tools force that into the database and particularly
> onto the end developer,   There's nothing even remotely close to Time
> Machine in OpenVMS, either.   Then there's that RMS is incapable of
> getting consistent live backups.
> 

You are missing the point.

Similar to asynch replication, and regardless of the OS platform, if one 
adopts write back caching strategies, you are saying that you are ok with 
potentially losing some data because the benefits of faster performance 
is worth the risk of losing some tbd amount of data and whatever prob's
that might create.

No platform, including OpenVMS, can ever state they will never lose 
data, but when the impact of lost or inconsistent data is high, you use 
sync replication and write through strategies to significantly reduce the 
risk.

These are not rocket science concepts.

[snip]


Regards,

Kerry Main
Kerry dot main at starkgaming dot com