Hi, Francisco,

The problem is that DSS query on secondary might take a lot of
CPU/disk resources that a requred to roll forward
logical log records received from the primary.

The first thing to do is to define whether it's CPU
or disk bottneck on the secondary

------------------------------------------
Alexey Sonkin
Senior Database Administrator


> -----Original Message-----
> From: Francisco Roldan [mailto:froldan@5b.com.gt]
> Sent: Friday, October 03, 2003 11:48 AM
> To: informix-list@iiug.org
> Subject: RV: Checkpoint Duration - HDR - Sync/Async
>
> Hi everyboy,
>
> I really would appreciate your comments about this subject.
>
> Thanks in advance
>
> -----Mensaje original-----
> De: Francisco Roldan [mailto:froldan@5b.com.gt]
> Enviado el: Miércoles, 01 de Octubre de 2003 12:30 p.m.
> Para: informix-list@iiug.org
> Asunto: Checkpoint Duration - HDR - Sync/Async
>
> Hi everybody,
> my environment :
>
> Two identical servers running AIX 4.3.3 - IDS 7.3.1 UD1
> running HDR between both database servers
> DRINTERVAL : 360 segs (=> ASYNCHRONOUS)
> I have only one production database on Buffered Logging Mode.
>
> I implemented HDR in order to protect the data changed after the last
> backup, and to be able to execute reports/DSS-querys on the secondary
> server (in that order).
>
> I read that the checkpoint between primary and secondary servers running
> HDR
> are synchronous, regardless of DRINTERVAL parameter is
> -1 (=> SYNCHRONOUS) or not.
>
> When i execute a very heavy dss query on my secondary server, it affects
> the
> performance on this server and i have noticed that it affects the duration
> of the checkpoint on both servers (even getting 6 times the normal
> duration).
> It is logic if i consider that the checkpoints between primary and
> secondary
> servers are synchronous, am i right ? or am i missing something else that
> could be affecting the checkpoints duration on both servers?
>
> Is it possible to minimize the impact on the primary server's checkpoint
> duration ? For examble by tunning some parameters like DRINTERVAL,
> CKPTINTVL(240 segs. on my servers), or the difference between these values
> (I am just guessing). Or the Logging mode on my only production database.
>
> Thanks in advance
>
> Regards
>
>
> sending to informix-list
>
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