Global journaling records all global update operations performed on a database, and used in conjunction with backup makes it possible to restore a database to its state immediately before a failure or crash.
While backup is the cornerstone of physical recovery, it is not the complete answer. Restoring a database from backup does not recover global updates made since that backup, which may have been created a number of hours before the point at which physical integrity was lost. These post-backup updates can be restored to the database from journal files after the database is restored from backup, bringing the database up to date. Any transactions open at the time of the failure are rolled back to ensure transaction integrity.
Journaling is a critical IRIS feature and a part of what makes IRIS a reliable database. While journaling is fundamental to IRIS, there are nuances, so I wrote this article to summarize (more briefly than our documentation which has all the details) what you need to know. I realize the irony of saying the 27 minute read is brief.
InterSystems has been at the forefront of database technology since its inception, pioneering innovations that consistently outperform competitors like Oracle, IBM, and Microsoft.
Working in support, I usually get asked how many days I should keep journals. Should it be two days or after two backups? More? Less? Why two?
The correct answer (for most of the environments) is that you should keep the journals since the last validated Backup. I.e., until you don't check if a Backup is valid (restoring the file and checking with the Integrity utility), you can't be sure there is a good copy of your data and can't purge the journals safely.
Following my previous post, some urged me to get to the point – ok, so I found my "star" journaling globals, the ones that take up the most space – but how do I avoid this? How do I minimize the journal's size?
[DISCLAIMER: Some might still be disappointed after this post as well but wait till the next one... ]
In this article, I'm excited to introduce my latest application, Journal File Indexer. The development of this application is rooted in the portal idea DPI-I-270.
In short, this application lets you load and index a log file in a database.
Why?
If you've ever used the log file search function in the management portal, you may have encountered a timeout error or even a blank page. This problem usually occurs when searching a large journal file. Journal File Indexer solves this problem by considerably increasing the speed of searches once the file has been loaded into the database.
Another problem arises during the restoration process. When searching for global entries in a log file to restore old or new values, the management portal doesn't have this specific functionality. A routine must therefore be coded to achieve this. Journal File Indexer comes to the rescue, incorporating a restore function!
Recently I needed to restore a version of a production class, which was overwritten by compilation and running UpdateProduction. As the correct version was unavailable in the source control, I used journals to restore the data. Journals store a plethora of information about what's happening in the system and are quite a powerful tool. This article explains how to work with journals to extract the data you require.
In this article I'd like to share with you a phenomena that is best you avoid - something you should be aware of when designing your data model (or building your Business Processes) in Caché or in Ensemble (or older HealthShare Health Connect Ensemble-based versions).
InterSystems has corrected a defect that causes invalid database and journal records to be introduced when using a specific $LIST syntax. The likelihood of encountering this defect is very low but the operational impacts can be significant.
I am still working on a generic task where I need to apply journal file records to another database. Initially I didn't want to use Journal.Restore class methods as I need to perform some data transformation, and it seemed that the clearest way to achieve it was to read journal file record by record using %SYS.Journal.Record API.
We have Mirroring established between NODE 1 & Node 2 . We have set the "cachesys" database enabled for Journalling. But we dont see the User Accounts , Roles, Resources created on Node 1 ( favoured Primary) reflected on Node 2 . Is creating them manually again is the only option for this ? . Is there any way to sync them or would adding %SYS to MIRROR a possible solution. Would it be great if anyone has faced this as we have an issue that during failovers Team is locked out .
My fantasy didn't go beyond periodically running %SYS.Journal.System:Progress() class query, while I'd prefer to use an event handler of some kind. Any ideas?
Is View Journal of Cache Management Portal the only way to search in Cache journals? I need a way to define several search conditions and Portal often breaks on http timeout.
I've stumbled on some unexpected behavior, and decided to check with you if this is normal. Basically, I'm rebuilding indices and the result is not journaling (which leads to missing indices at shadow server).
The $ZV is "Cache for UNIX (Red Hat Enterprise Linux for x86-64) 2015.2.1 (Build 705U) Mon Aug 31 2015 16:53:38 EDT"
I have an example class
Class tmp.A As %Persistent;
Index IP1 On P1;
Property P1 As %String;
for example there is one object which have P1 = 1, so
For I=1:1:200 Set ^ABC(I)="" For I=1:1:200 Set ^XYZ(I)="" For I=1:1:100 Kill ^ABC(I)
2. create ZJRNFILT
ZJRNFILT(jid,dir,glo,type,restmode,addr,time) /*Filter*/ Set restmode=1 /*Return 1 for restore*/ If glo["^ABC",type="K" Set restmode=0 /*except if a kill on ^ABC*/ Quit ;
Our mirrored HealthShare environment has failed over a few times recently due to underlying infrastructure issues (that are being worked on and resolved).
In the HealthShare logs we are seeing:
10/06/22-00:54:35:925 (4736) 1 Journal Daemon has been inactive with I/O pending for 10 seconds: gjrnoff=524741316,iocomplete=523852600,filecnt=1011,fail=0 10/06/22-00:54:55:086 (4736) 3 CP: Pausing users because Journal Daemon has not shown signs of activity for 30 seconds. Users will resume if Journal Daemon is active again
In the Windows Ressource Manager I can observe multiple parallel processes coming from cache.exe with read operations to journaling files.
All except one of these processes have the same reads(Byte/s). The processes point to different journal files and constantly read between 200 and 3000 Bytes/s.
The corresponding process via PID in the management portal of Caché shows the process %SYS.Monitor.Control.1. In 3 days of uptime on the server it has run 181.632.583 commands and modified 32.140.642 globals.
Just wondering if anyone knows if there is a way to get daily emails or alerts about changes to a cache database. I know that all of that information is contained within the journal files, just wondering if there is a way to bundle it up each day and send it off for auditing, etc.
Any solution where a plain-text/readable format of changes to the cache database could be sent or stored for review would solve the issue.
I'm a DBA and support Caché databases on AIX. I coded shell scripts for monitoring journaling status, databases size, license end date.
We recently got a new instance of Caché on Windows. I'm just curious to know whether anyone coded database monitoring scripts on Windows using PowerShell or any other scripting language.
I have several 1GB journals from a LIVE server that I would like to inspect (eg: check which globals have been updated over the time).
Is there a simple way to view those journals using another IRIS instance ? (eg: local installation).
I have been tempted to put those files directly into the journal folder of my local installation and restart the system, however I am concerned that the transactions they contains will be restored and will corrupt the local database.
By likes
Open Exchange app
but wait till the next one... ]