Third Time’s The Charm For SRB – Or Is it?

Passing reference to Blondes Have More Fun – Or Do They?.

Yeah, I know, it’s a tortuous link. 🙂 And, nah, I never did own that album. 🙂

I first wrote about System Recovery Boost (SRB) and Recovery Process Boost (RPB) in SRB And SMF. Let me quote one passage from it:

It should also be noted that when a boost period starts the current RMF interval stops and a new one is started. Likewise when it ends that interval stops and a new one is started. So you will get “short interval” SMF records around the boost period.

I thought in this post I’d illustrate that. So I ran a query to show what happens around an IPL boost. I think it’s informative.

RMF Interval Start Interval Minutes Interval Seconds IPL Time (UTC) IPL Time (Local) zIIP Boost Note
May 9 07:58:51 5:02 302 May 2 07:13:08 May 2 08:13:08 No 1 2 3
Down Time May 9 07:58:51 – 08:15:01
May 9 08:19:50 9:03 543 May 9 07:15:01 May 9 08:15:01 Yes 4
May 9 08:28:54 15:00 900 May 9 07:15:01 May 9 08:15:01 Yes 5
May 9 08:43:55 15:00 900 May 9 07:15:01 May 9 08:15:01 Yes 5
May 9 08:58:55 15:00 900 May 9 07:15:01 May 9 08:15:01 Yes 5
May 9 09:13:55 1:31 91 May 9 07:15:01 May 9 08:15:01 Yes 6
May 9 09:15:25 13:29 809 May 9 07:15:01 May 9 08:15:01 No 7
May 9 09:28:55 15:00 900 May 9 07:15:01 May 9 08:15:01 No 8

Some notes:

  1. UTC Offset is + 1 Hour i.e. British Summer Time.
  2. IPL time was a week before.
  3. For some reason there was no shutdown boost.
  4. This is a short interval and the first with the boost. And note RMF starts a few seconds after IPL.
  5. These are full-length intervals (900 seconds or 15 minutes) with the boost.
  6. This is a short final interval with the boost.
  7. This is a short interval without the boost – which I take to be a form of re-sync’ing.
  8. This is a return to full-length intervals.

So you can see the down time between RMF cutting its final record and the IPL. Also between the IPL and RMF starting. You can also see the short intervals around starting and stopping the boost period.

Here’s an experimental way of showing the short intervals and the regular (15 minute) intervals.

The blue intervals are within the boost period, the orange outside it.

I don’t know if the above is helpful, but I thought it worth a try.

I don’t know that this query forms the basis for my Production code, but it just might. And I remain convinced that zIIP boosts (and, to a lesser extent, speed boosts) are going to be a fact of life we are going to have to get used to.

Finally, I’ll also admit I’m still learning about how RMF intervals work – so this has been a useful exercise for me.

Of course, when I say “finally”, I only mean “finally for this post”. I’ve a sneaking suspicion I’ve more to learn. Ain’t that always the way? 🙂

Published by Martin Packer

I'm a mainframe performance guy and have been for the past 35 years. But I play with lots of other technologies as well.

2 thoughts on “Third Time’s The Charm For SRB – Or Is it?

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: