Friday, July 20, 2012

Holiday, back somewhere in August

I just realized that the last two years I had quite a busy time just before my holidays as each time I was preparing all kinds of texts and customer presentations for a new system that was announced that summer. In 2010 we had the introduction of the zEnterprise (z196, zBX and zManager) and last year there was the introduction of the z114. So , I hope I don't disappoint you too much, but I haven't seen any new announcements this time.

I have another blog where I advise people not to touch any computer (or other related device) for a couple of weeks during their holdiays and that's exactly what I intend to to for al least the next two weeks. How hard can it be ?

Well, I have a lot of books waiting to be read.

So thanks for stopping by so regulary and have a nice holiday !

Thursday, July 19, 2012

Possible DS8700/DS8800 abort condition during zOS writes to a FlashCopy target when experiencing uncorrectable SAN link errors

I'm just reproducing this Flash (alert) which you can find over here.

In certain circumstances, CKD (zOS) host writes to a FlashCopy Target in conjunction with uncorrectable SAN link errors can result in repetitive microcode logic errors and possible loss of access to the DS8700/DS8800.

The issue specifically requires a combination of CKD writes to a FlashCopy Target volume in addition to uncorrectable SAN link errors. Most notable use for a zOS

Host to write to a FlashCopy Target is during disaster recovery testing in a Global Mirror (GM) or Metro Global Mirror (MGM) environment. Typically, for disaster
recovery tests, at the Global Mirror secondary, a practice copy will be created from the consistent copy of the data. This practice copy is then made available for
Host I/O directly to it.

Another common use for a FlashCopy target, tape backup, is not affected by this issue as tape backup only does Host reads and not writes.

Release 6.1, Release 6.2 (prior to Service Pack 2.1), Release 6.3 (prior to Service Pack 1) on the DS8700 and DS8800 platforms are affected.

Two aspects of mitigation for this problem:

1. Avoid any activity which involves CKD I/O to a FlashCopy Target. Avoid disaster recovery testing in Global Mirror environments which involve using a practice
copy from the Global Mirror target until fix is delivered.

2. In the case of an actual disaster where the Global Mirror primary site is no longer available, the user can invoke a fast reverse restore from the consistent copy
(D volume) of the data back to the C volume and run the zOS host specifically to the C volume. The C volume in this example is not a FlashCopy target, it is a
regular volume.

Note: If the application waits for the background copy to complete prior to initiating other CKD writes to the FlashCopy Target volume, there is no risk of the abort mentioned above.

A fix has been available in microcode bundles or higher for DS8700s and in or higher for DS8800s. A fix is also now available in release 6.3 microcode bundles or higher for DS8700s and in or higher for DS8800s.

CICSdev Community

Don't you hate it too ? You're looking at a site which has (flashy !, flashy !!) a new holiday promotion. But when you're looking a bit closer, it turns out to be for 2009. To quote Homer : "Duh!". So when last week my sister asked me about setting up a website for a club we started to discuss the content of the site. So far, so good. But then I pointed out we hadn't talked about the most important part of it : updating and maintaining the website. Regularly adding new content, updating the agenda, removing older items etc. etc. Ouch ! So this means you have to at least once a week spend time maintaining the thing. Yes, it does. And if you don't : no information, no visitors, no nothing. So the idea was put to rest there and then.

For the same reason, I'm always a bit sceptical when I'm looking at yet another new community site. We've seen them come and go or perhaps rather stay but with no interesting content after a while.

But this one, that's apparently active since the beginning of the year, seems to be different : CICSdev or The CICSdev community. As they say themselves : "The CICSdev Community is the place to discuss, share and learn about developing for CICS". Well, I must say, it looks good : very easy navigation but also very interesting content. There's a blog that's e.g. mentioning on July 13 that the CICS TS V5.1 open beta, I also wrote about, is now available for download. There's a download tab where you find the information where to download this beta and the CICS TS V4.2 Developer Trial I also talked about earlier. There's a learning tab with articles, videos and presentation. I also like the participation tab. Did you know there's a forum ? I also found out (shame on me) , there's a CICS discussion list just like e.g. the IBM-MAIN list. If you're looking for the links, I deliberately let them out. So you have to go and have a look for yourself.

I hope I didn't put the expectations too high, or perhaps I do. So keep coming with new and interesting content !

Tuesday, July 10, 2012

Holiday Reading : IBM Systems Magazine and Enterprise Tech Journal

You might think that we have a new magazine on the block. Well, not really z/Journal (previously Enterpise Systems Journal, previously Mainframe Journal) is now called Enterprise Tech Journal in order "to reflect the changing dynamic of today's hybrid data centers". So it will have a broader perspective on multi-platform technologies in the enterprise, but still remain mainframe-centric. The articles that drew my attention were mainly the technical ones like 'CICS Transaction Gateway V8.1 : What's new and why it matters' by Paul Crockett and a good overview of Temporal Tables in DB2 by Dan Luksetich.
You'll also find a very good introduction to z/VM Live Guest Relocation (LGR) by Mark Lorenc : "The LGR function (...) can be useful for a mainframe shop running Linux applications on z/VM that require non-stop availability". And there's a column by Marcel den Hartog on "How to put a smile on the CIO's face'. If that isn't worth a look . . .
You can download the digital version over here.

IBM Systems Magazine has amongst others some interesting articles on consolidation to the mainframe. Greg Lotko tells us about the IBM vision on consolidation in 'The Performance of Many, The Efficiency of One' (you just have to love this title, don't you). He also tells about some significant differences between a DIY environment and one with zBX and Unified Resource Manager.
The next article 'Mainframe vs. Distributed' tells you about how to make a correct TCO study comparing apples with apples and warning you about some pitfalls ranging from faultive chargeback mechanisms to including "the corporate jet in the mainframe costs!" Yes, it's really there !
Then two interesting examples of consolidating on Linux on z. One of them is IBM itself and the other is Shelter Insurance. Go and read them : I'm sure you'll like the down to earth approach of Shelter Insurance.
You can find the digital version over here.

As I always say, just check them out !

Thursday, July 5, 2012

z/VM turns 40 next month : some history and a new blog

IBM announced its first official VM product (then called VM/370) on August 2, 1972. As times changed, so did VM. You may have known it by one or more of its many flavors (VM/SP, VM/XA, VM/SP HPO, VM/IS, VM/ESA) that preceded today's z/VM. So, z/VM is turning 40 next month.

If you want to learn some more on the history of VM, there's already a VM History and Heritage Reference page over here.

This anniversary seems to have been a good reason for Bill Bitner to start a blog on this called : '40 Reflections for 40 Years of z/VM'. You can find it over here. The author's intentions ?
As the IBM z/VM product approaches its 40th Anniversary on August 2, 2012, the author takes time to reflect on the product and his experiences.
Go and have a look at it. One of the questions that, obviously, pops up is "What is a VM?". In another post Bill refers to Brian Wade's phrase saying it is z/VM's role to "faithfully replicate the architecture". He also comments on the z/VM community, the people behind the product (IBM, customers), influential people etc.
I think I'll pass the link along to my VMWare colleagues as well. After all they might be interested in how VMWare will evolve the next 30 years.

As I always say, just check it out !

Tuesday, July 3, 2012

Want to be part of a System z Poster ?

I saw this passing by on Twitter yesterday : you can submit your picture on this site and you might become one of the 150 faces on a new System z Poster. Even if you're not selected, you might be interested to participate as every participant will receive a printed poster afterwards. You have time until July 31, 2012 to submit your picture.

This is how the poster will look like, and, ok, ok, with some wishful thinking I made a little change to this one.

Monday, July 2, 2012

Red Alert : JES2 Potential Loss of Spool data on z/OS 1.11 and 1.12

Here's a new Red Alert:

JES2 Potential Loss of Spool data on z/OS 1.11 and 1.12

The fix for APAR OA36256 (RSU1112 PTFs UA61942, UA61943 UA61944 on HJE7760, HJE7770, and HJE7780 respectively) widened a timing window during JES2 initialization processing such that an initializing JES2 member may not obtain the correct status of other multi-access spool (MAS) members. As a result, this system's view of a spool volume may differ from the rest of the MAS. Consequently, later HALTING or DRAINING actions against the spool volume may result in incomplete cleanup.

PE APAR OA39737 will address the timing window and ensure the initializing member has the most accurate status of the MAS during initialization. In addition, APAR OA38016 will address spool errors caused by the timing window that may result in potential loss of spool data. These types of spool errors are already corrected in z/OS 1.13.

Please see OA39737 and OA38016 for more details or updates.

Recommended Actions:
  • If PTF for OA36256 is applied, please avoid putting a spool volume into DRAINING or HALTING state. New volumes can be added or started without exposure.
  • If a Spool Drain or Halt must be done, Level 2 can check dumps of JES2 to determine if the spool volume is exposed.
  • If OA36256 is applied and a spool volume is already in DRAINING or HALTING state, please remove OA36256 and then (rolling) WARM start each JES2 member.

If you want to have an overview of all past Red Alerts, then take a look over here. You can also subscribe on that same page so you'll be notified of any future Red Alert.