Jon,
I think might be confused with the Enhanced Chkpoint first enabled in 6.0 and
subsequently taken away because it does not support files greater than 4GB.
I think it was a great idea, and did help in 6.0. butit is no longer
available. Adjusting the priority of the checkpoint, can help but not if it
slows the checkpoint down to the point of collision with the next checkpoint.
-Craig
--- JON OSE <[log in to unmask]> wrote:
> Is anyone using this feature first installed in 6.0?
>
> alterchkptstat <volset-name> ENABLE | DISABLE
>
> This feature remembers the dirty page ranges for each XM attached open file,
> it can't affect files that were open before giving this request. It will take
> effect for the files that were first fopened after giving the request. The
> best way to enable or disable this Checkpoint Improvement feature is to
> reboot the machine after entering the command.
>
> Jon
>
>
> Craig Lalley <[log in to unmask]> wrote:
> Denys,
>
> During the checkpoint the XM will scan memory for dirty pages to post. This
> is
> the notorious pin 11 or 12 that people see periodically on the system (pin 17
> for N-class boxes).
>
> Scanning memory creates a lot of system overhead and there is a patch to
> reduce
> the effect of semaphore locking (MPEMX34A probably superseeded).
>
> The real problem is when the second Checkpoint hits, before the first has
> time
> to finish, i.e. they collide. To compensate for this, it is possible to
> increase the size of the XM logfile and reduce the time between checkpoints.
>
> The good news is that the XM checkpoint is a serially threaded process, hence
> it will only use up one processor (better have a few if you have 16GB of
> memory).
>
> The problems I am discussing are for very heavy, data entry systems. The XM
> (transaction manager) is a write cache.
>
> Generally more memory will help batch reporting, it does not always help
> on-line response times.
>
> Hope that makes sense, it took me awhile to understand it.
>
> -Craig
>
>
> --- Denys Beauchemin wrote:
> > Ok, explain how that would be painful.
> >
> > Denys
> >
> > -----Original Message-----
> > From: HP-3000 Systems Discussion [mailto:[log in to unmask]]On
> > Behalf Of Craig Lalley
> > Sent: Tuesday, February 03, 2004 8:28 AM
> > To: [log in to unmask]
> > Subject: Re: [HP3000-L] 997 and memory
> >
> > Chuck, Dane, Joe and all,
> >
> > I humbly beg to differ, a 997 supports 16 GB of memory with standard HP
> > memory.
> >
> > Although I do not recommend it. The problem is the 180Mhz 997
> > processor. At
> > 180 Mhz, it takes about 80 seconds to scan 16GB of memory. That could
> > make the
> > XM checkpoints quite painful.
> >
> > -Craig
> >
> >
> > --- Chuck Ciesinski wrote:
> > > Dane, Joe, and all,
> > >
> > > I humbly beg to differ with Joe, with third party arrays, you can get
> > 16
> > > GB in a 997.
> > >
> > >
> > > Chuck Ciesinski
> > > Hughes Network Systems
> > > 11717 Exploration Lane
> > > Germantown, MD 20876
> > > p 301 601 2608
> > > f 301 601 6303
> > > email [log in to unmask]
> > > "The joy of life is living it..." unknown
> > >
> > > * To join/leave the list, search archives, change list settings, *
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> >
> >
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