× The internal search function is temporarily non-functional. The current search engine is no longer viable and we are researching alternatives.
As a stop gap measure, we are using Google's custom search engine service.
If you know of an easy to use, open source, search engine ... please contact support@midrange.com.


  1.  Home
  2. MIDRANGE-L
  3. August 2017

Re: [IE] Re: Mirroring by RRN slow for large file

Hi Peter

What does the disk activity look like on the target system ? Is there any
indication of an IO hardware bottle neck ?

WRKDSKSTS may give you some indication of whether this is an issue or maybe
one of the disk graphs from Naviator for i (presuming you have the
performance collector running on the target)

On Tue, Aug 15, 2017 at 9:12 AM, Peter Connell <Peter.Connell@xxxxxxxxxxx>
wrote:

Thanks Augie,

We ensure that there are no batch jobs on the apply side that use much
CPU. Any jobs that do run are mostly read only an any updates are to
non-journalled files.
Most of the time the only thing running is iTera replication.

All access paths are *immed. There is no EDTRDBAP object and I've never
seen any access path rebuilding occurring.
Yes, there has been a virtual role swap about a year back when we never
noticed this latency.

The large files were changed to *SSD storage a few months back but that
should only improve things.
We don't have SSD on the apply system. The large file in question has
storage unit *ANY there.
I've just noticed that, of the 16 files that are in SSD on the source
system, 6 of them also had *SSD on the apply system. Not sure if that
matters but they're all now *ANY on the apply system.

Regards, Peter

-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of
Augie Palumbo
Sent: Monday, 14 August 2017 6:25 AM
To: Midrange Systems Technical Discussion
Subject: [IE] Re: Mirroring by RRN slow for large file

Hi Pete,


Generally speaking the only time you should see latency on the apply side
is:

Resources. CPU/Memory
iTera was down for a time
Commitment Control
Locking of files - i.e other jobs running on the target for perhaps read
only functions Large batch job generating many transactions in a short time.


The latency of data on the apply side shouldn't be happening but it
nothing to do with RRN processing vs keyed. I assume all of the access
paths are are *IMMED for update and none of them ate *DELAY.

EDTRBDAP will tell you if the system is rebuilding access paths. If it is
this would cause a transaction to queue but only until the access path was
re-built. Once it was then it should fly threw the data. I've seen upwards
of billions of transactions a day and no latency.

Has this always happened? Was there an event that may have caused this?
Have you ever done a role swap? or even a virtual role swap?

Product like iTera have been out for over 25 years now and have proven
methods of applying data. I suspect there is something else happening that
is causing the delay..

Thanks
Augie

Augie Palumbo
312-735-3723
702-826-2836

On Sun, Aug 13, 2017 at 8:02 AM, Nathan Andelin <nandelin@xxxxxxxxx>
wrote:

Peter,

I haven't actually tested the performance of RRN vs. keyed index
access on IBM i, but the IBM i index search may actually return a RRN
if it works like some of the other DBMS products I've worked with. So
a known RRN may be the quickest way to find records.

I'm not that familiar with iTera, but I wonder if it may have a
configuration setting that controls the queue on the target system?

Nathan.


On Sat, Aug 12, 2017 at 11:39 PM, Peter Connell
<Peter.Connell@xxxxxxxxxxx

wrote:

I assume that mirroring software (ITERA) that uses journals for
replication to another IBM i5 performs updates and deletes on the
target system by using the RRN stored in each journal to replicate
the update or delete.
This is a reasonable assumption since the mirroring software knows
nothing
about any index it might use to achieve the update of delete via an
access
path.

A large file on the source system of 170 million records which may
attract
several million updates and deletes in a day results in these being
queued
for long periods on the target system before the actual replication
event occurs to keep the file in synch.
I presume that the substantial latency observed between the source
and target updates and deletes is because the record be updated or
deleted is being located via RRN.
Perhaps this is because DB2 has to do a table scan to find the
record which is slower than an update via a unique index.

It's not clear if creating an index whose primary key is RRN would
help otherwise the only solution may be to do a custom replication
that reads the journal, and extracts the unique index to do an update
or delete.

Regards, Peter

############################################################## This
correspondence is for the named person's use only. It may contain
confidential or legally privileged information, or both. No
confidentiality
or privilege is waived or lost by any mistransmission. If you
receive
this
correspondence in error, please immediately delete it from your
system
and
notify the sender. You must not disclose, copy or rely on any part
of
this
correspondence if you are not the intended recipient. Any views
expressed in this message are those of the individual sender, except
where the
sender
expressly, and with authority, states them to be the views of
Equifax. If you need assistance, please contact Equifax :- Australia
www.equifax.com.au/contact New Zealand www.equifax.co.nz/contact
##############################################################
--
This is the Midrange Systems Technical Discussion (MIDRANGE-L)
mailing
list
To post a message email: MIDRANGE-L@xxxxxxxxxxxx To subscribe,
unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx Before posting, please
take a moment to review the archives at
http://archive.midrange.com/midrange-l.

Please contact support@xxxxxxxxxxxx for any subscription related
questions.

Help support midrange.com by shopping at amazon.com with our
affiliate
link: http://amzn.to/2dEadiD

--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing
list To post a message email: MIDRANGE-L@xxxxxxxxxxxx To subscribe,
unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx Before posting, please take
a moment to review the archives at
http://archive.midrange.com/midrange-l.

Please contact support@xxxxxxxxxxxx for any subscription related
questions.

Help support midrange.com by shopping at amazon.com with our affiliate
link: http://amzn.to/2dEadiD

--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing
list To post a message email: MIDRANGE-L@xxxxxxxxxxxx To subscribe,
unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx Before posting, please take a
moment to review the archives at http://archive.midrange.com/midrange-l.

Please contact support@xxxxxxxxxxxx for any subscription related
questions.

Help support midrange.com by shopping at amazon.com with our affiliate
link: http://amzn.to/2dEadiD
############################################################## This
correspondence is for the named person's use only. It may contain
confidential or legally privileged information, or both. No confidentiality
or privilege is waived or lost by any mistransmission. If you receive this
correspondence in error, please immediately delete it from your system and
notify the sender. You must not disclose, copy or rely on any part of this
correspondence if you are not the intended recipient. Any views expressed
in this message are those of the individual sender, except where the sender
expressly, and with authority, states them to be the views of Equifax. If
you need assistance, please contact Equifax :- Australia
www.equifax.com.au/contact New Zealand www.equifax.co.nz/contact
##############################################################
--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list
To post a message email: MIDRANGE-L@xxxxxxxxxxxx
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx
Before posting, please take a moment to review the archives
at http://archive.midrange.com/midrange-l.

Please contact support@xxxxxxxxxxxx for any subscription related
questions.

Help support midrange.com by shopping at amazon.com with our affiliate
link: http://amzn.to/2dEadiD





As an Amazon Associate we earn from qualifying purchases.

This thread ...
Replies:
Follow On AppleNews
Return to Archive home page | Return to MIDRANGE.COM home page

This mailing list archive is Copyright 1997-2024 by midrange.com and David Gibbs as a compilation work. Use of the archive is restricted to research of a business or technical nature. Any other uses are prohibited. Full details are available on our policy page. If you have questions about this, please contact [javascript protected email address].

Operating expenses for this site are earned using the Amazon Associate program and Google Adsense.