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BaltoStar_12467's avatar
BaltoStar_12467
Nov 02, 2014

BIG-IP : best practice to update HA pair under load

F5 BIG-IP Virtual Edition v11.4.1 (Build 635.0) LTM on ESXi

 

For an HA pair configured as sync-failover device-group with auto-sync enabled, what is best practice to apply config changes ( including irules and data-group-files ) ?

 

I can think of a two possible mechanisms :

 

  1. disable auto-sync; apply changes to active device; if changes working as expected, re-enable auto-sync; if not, failover from active to standby, re-enable auto-sync

     

  2. disable auto-sync; apply changes to standby device; if changes working as expected, failover from active to standby, if succeeds re-enable auto-sync; if changes not working as expected, force-sync active to standby, re-enable auto-sync

     

And is it possible to implement these mechanisms via iControl ? Can iControl submit failover command ? Is it sensible to do so ? What is expected time for failover to occur ?

 

application delivery
availability
devops
iControl
iRules
LTM
management

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  • nitass's avatar
    nitass
    Icon for Employee rankEmployee
    Nov 02, 2014

    i prefer the second one.

    2. disable auto-sync; apply changes to standby device; if tests show changes working as expected, failover standby to active, re-enable auto-sync; if not, failover active to standby, re-enable auto-sync.

    i am not familiar with icontrol, so i leave it to the next guy. 🙂

  • Mohamed_Lrhazi's avatar
    Mohamed_Lrhazi
    Icon for Altocumulus rankAltocumulus
    Nov 02, 2014

    I work in an environment with lots of LTMs pairs with auto-sync enabled. They are being modified on regular basis, no one ever thought about disabling auto-sync, not even during upgrades. Why did you even think about doing this?

     

  • R_Marc's avatar
    R_Marc
    Icon for Nimbostratus rankNimbostratus
    Nov 02, 2014

    You can do the auto-sync toggling and failovers via iControl (at least the rest interface, I've never tried the SOAP version).

     

    As I recall from some training courses, however, F5 recommended taking a config backup as the preferred method of change backout (which also could be done from iControl). I think that is operationally less risky than what you have outlined here. I have run into a lot of sync issues on my devices (mostly fips related, may not apply to you) so I'd be leery of flipping that auto-sync bit a lot.

     

    Also, when you fail over, you are likely to loose in flight transactions. I'm fighting with that right now; Whereas on a restore from backup should only touch those items you've changed. I have not tested this, of course, so your mileage may vary.