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| RDQM and connectivity from z/OS QM |
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| zpat |
 Posted: Wed Jan 22, 2025 6:24 am Post subject: RDQM and connectivity from z/OS QM |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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RDQM means there are three Linux hosts where the RD QM might be running (on one of them only).
Issue 1
To code three hosts addresses in a z/OS sender channel is impossible in the 48 characters allowed (including the port numbers).
The obvious answer is to use RQDM floating IP (rdqmint) command - is that correct - any other solutions?
Issue 2
Should the RDQM also be in a MQ cluster - it would need a cluster receiver channel defined. What connection address should be coded there? - I am guessing it could be the floating IP or a list of the three hosts?
Issue 3
If the Linux RDQM had a cluster receiver channel with a connection string greater than 48 characters - what happens when a z/OS QM wants to dynamically connect a cluster sender channel? Does it work or not?
No prizes on offer other than the kudos of being right  Assume MQ 9.2 or 9.3 is being used.
Has anyone use DNS to abstract/ load balance a RDQM?
Has anyone used a F5 to load balance a RDQM (MQ protocol with TLS).
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Well, I don't think there is any question about it. It can only be attributable to human error. This sort of thing has cropped up before, and it has always been due to human error. |
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| fjb_saper |
| Posted: Thu Jan 23, 2025 6:37 am Post subject: Re: RDQM and connectivity from z/OS QM |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| zpat wrote: |
RDQM means there are three Linux hosts where the RD QM might be running (on one of them only).
Issue 1
To code three hosts addresses in a z/OS sender channel is impossible in the 48 characters allowed (including the port numbers).
The obvious answer is to use RQDM floating IP (rdqmint) command - is that correct - any other solutions?
Issue 2
Should the RDQM also be in a MQ cluster - it would need a cluster receiver channel defined. What connection address should be coded there? - I am guessing it could be the floating IP or a list of the three hosts?
Issue 3
If the Linux RDQM had a cluster receiver channel with a connection string greater than 48 characters - what happens when a z/OS QM wants to dynamically connect a cluster sender channel? Does it work or not?
No prizes on offer other than the kudos of being right Assume MQ 9.2 or 9.3 is being used.
Has anyone use DNS to abstract/ load balance a RDQM?
Has anyone used a F5 to load balance a RDQM (MQ protocol with TLS). |
AFAIK this is all a moot point as RDQM is only for RHEL Linux. As such there is no 48 char limitation for the conname... 
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| zpat |
| Posted: Fri Jan 24, 2025 3:29 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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Yes, but we have a Z/OS QM that needs to connect to the Linux RDQM.
The z/OS sender channel DOES have a 48 character limitation.
| Quote: |
The generated CONNAME is always in the dotted decimal (IPv4) or hexadecimal (IPv6) form, rather than in the form of an alphanumeric DNS host name.
The maximum name length depends on the platform:
[UNIX, Linux, Windows, IBM i]264 characters.
[z/OS]48 characters
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I am not suggesting using z/OS to host a RDQM.
_________________
Well, I don't think there is any question about it. It can only be attributable to human error. This sort of thing has cropped up before, and it has always been due to human error. |
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| fjb_saper |
| Posted: Thu Jan 30, 2025 5:56 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| zpat wrote: |
Yes, but we have a Z/OS QM that needs to connect to the Linux RDQM.
The z/OS sender channel DOES have a 48 character limitation.
| Quote: |
The generated CONNAME is always in the dotted decimal (IPv4) or hexadecimal (IPv6) form, rather than in the form of an alphanumeric DNS host name.
The maximum name length depends on the platform:
[UNIX, Linux, Windows, IBM i]264 characters.
[z/OS]48 characters
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I am not suggesting using z/OS to host a RDQM. |
I suggest that you create a DNS alias that is shorter then the RDQM DNS but points to the same address / service. (RDQM in RHEL Open Shift).
Alternatively., if the ips are fixed, you could use a CCDT with one entry per hostname...
If you need a sender connection use the single floating ip.
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| zpat |
| Posted: Fri Jan 31, 2025 7:08 am Post subject: |
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Jedi Council
Joined: 19 May 2001
Posts: 5866
Location: UK
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Yes, DNS was my first suggestion when they asked us to code 6 host names in the connection name field of a z/OS channel (2 sites x 3 hosts).
However we really need not just one DNS for each IP - but one DNS referring to the active RDQM host after failover.
rdqmint is the obvious solution to avoid manual DNS updates (too slow in a HA failover). Has anyone used this?
Interestingly the 48 character limitation also applies to z/OS MQ dynamic cluster sender channels. It picked up the massive 6 host string that was coded on the Linux RDQM MQ cluster recievers but could only use 48 characters on the z/OS side, so that's another one to look out for.
In other words if your Linux RDQM hosted MQ cluster need to be connected to from z/OS QMs - keep the conname contents down to 48 characters.
This annoying conname max length mismatch is no doubt being addressed by IBM but even if it was fixed in the next version of z/OS MQ - it would take around 2 years for us to install it as a LTS version.
_________________
Well, I don't think there is any question about it. It can only be attributable to human error. This sort of thing has cropped up before, and it has always been due to human error. |
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| fjb_saper |
| Posted: Sun Feb 02, 2025 5:28 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| zpat wrote: |
Yes, DNS was my first suggestion when they asked us to code 6 host names in the connection name field of a z/OS channel (2 sites x 3 hosts).
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So you are doing RDQM/DR?
| zpat wrote: |
However we really need not just one DNS for each IP - but one DNS referring to the active RDQM host after failover.
rdqmint is the obvious solution to avoid manual DNS updates (too slow in a HA failover). Has anyone used this?
Interestingly the 48 character limitation also applies to z/OS MQ dynamic cluster sender channels. It picked up the massive 6 host string that was coded on the Linux RDQM MQ cluster recievers but could only use 48 characters on the z/OS side, so that's another one to look out for.
In other words if your Linux RDQM hosted MQ cluster need to be connected to from z/OS QMs - keep the conname contents down to 48 characters.
This annoying conname max length mismatch is no doubt being addressed by IBM but even if it was fixed in the next version of z/OS MQ - it would take around 2 years for us to install it as a LTS version. |
You will have to find creative ways around it, such as using a globally defined alias less then 24 chars... so you can have "alias1(port),alias2(port)" as conname, the alias pointing to the running qmgr...
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