Shield Boosts Performance, Flexibility with HA4i 7.1
Published: October 9, 2012
by Alex Woodie
Shield Advanced Solutions is rolling out a new release of its high availability software for IBM i, HA4i 7.1. The new version sports a brand spanking new journal apply process that Shield says gives its customers more flexibility in how they configure their high availability environments when compared to the traditional IBM apply process. The extensive testing phase of HA4i 7.1 also revealed a performance boost in some situations, the company says.
HA4i is a logical replication high availability solution that's based on IBM's remote journaling technology. When it started out in 2007 under the name Receiver Apply Program (RAP), the software focused on replicating database files and key objects to secondary machines for disaster recovery (DR) purposes. Over the years, Shield shaped the software into a higher grade HA product with the addition of synchronization checks, auditing tools, automated discovery of new objects, job monitoring, IFS support, and support for user profiles, among other objects.
In 2010, Shield renamed the product HA4i, which it released at version 6.1. The big change that Shield touted in version 6.1 was a new journal apply method that implemented a separate apply process for each configured journal, thereby delivering greater granularity and control of the product. A new PHP-based user interface and support for PF-SRC (source physical files) were also unveiled.
Now, two years later, Shield is tweaking the journal apply process again with the introduction of its direct apply technology and the related *SAS command. The company says its *SAS command updates the objects directly from the remote journal content, which gives it more control over the apply process and a way around the limitations imposed by IBM's traditional APYJRNCHG command.
Shield president Chris Hird explained the requirements behind the change in technology in his blog. "The existing apply process is an excellent technology and it meets most of our existing clients needs, but the inflexibility of IBM in terms of new features and enhancements to that process started to provide a number of challenges, which we found difficult to work around, if in fact we could," he writes. "The direct apply process (*SAS) does not suffer from that inflexibility so we can manipulate the technology to meet the clients requirements."
Specifically, Hird cited the benefits that the new *SAS technology will bring for customers still running i5/OS V5R4, and the challenges they faced maintaining a clean relationship between physical file and logical file when using the APYJRNCHG process. He says that problem is "now solved. The objects will be created in the correct sequence."
The new *SAS apply process will also provide a performance boost for IBM i shops that configure their applications in certain ways. This is due to how the APYJRNCHG process locks all of the files attached to the journal before processing an update. If the customer has a whole lot of files attached to that journal--like in the tens of thousands--then it can take a long time to lock all those files before processing an update.
"This was, in fact, one of the major reasons we decided to create our own apply process so we could control just what was locked and when, especially as IBM was unwilling to change any of their processes which we relied on," Hird says. "The new apply process now locks a file only when it has updates to apply. This has provided us with tremendous catch-up capabilities, because it is only opening files as updates are seen."
Hird related the case of a client with more than 30,000 files defined to a single journal. "With the new apply [process], the most files we have ever seen open is just over 200. This means the journal has over 29,800 files which are never updated, yet would have required locking each and every time the IBM [APYJRNCHNG] apply process was run."
Shield had to do some clever programming to figure out how to handle triggers, but it eventually did. The company says that *SAS supports triggers and commitment controls, and will reuse deleted record files regardless of the apply process used.
HA4i customers can use the new *SAS or the old APYJRNCHG apply processes within the same HA environment. Some applications (like the client's mentioned above) may work better with one apply process or the other, and Shield says it made an effort to make it easy for users to switch between the two modes.
"The new apply process will apply changes directly from the remote journal in much the same way most of our competitors do," Hird writes. "This means we now offer the client a choice on how they want to apply journal changes. This is something no one else offers."
HA4i 7.1 brings a few other new features, including updates to the auditing and automated repair functions. Through the end of the year, Toronto, Ontario, company is providing a discount on the special version of Job Queue Genie for HA4i (called JQG4i), which provides automated recovery of IBM i job queues in the event of an outage or failover. For more information, see the company's website at www.shieldadvanced.ca.
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