POOL OF LAST RESORT

Question

I want to create a pool of last resort.. meaning i have pool with 3 members and the business wants to do maintenance on those 3 member nodes but during that time they want to direct it to a different pool so they can say "site is under contruction" &nbsp;
&nbsp;Question. Is there a way to do this without iRules but some setting with the virtuals or pool itself. I was thinking last hop pool under the virtual setting. Will that work? or is there a better way? BTW no GTMs only a pair of 3600 LTM&nbsp;
&nbsp;LTM  BIG-IP 10.2.0 Build 1707.0 Final

hoolio · Answer

Hi Jeff, &nbsp;
&nbsp; There are a few options: &nbsp;
&nbsp; - Use the HTTP profile fallback URL option to send the client a redirect to a new URL when the load balancing attempt fails. &nbsp;
&nbsp;- Use pool member priority so that if the higher priority pool members are down, a lower priority maintenance pool will be used.&nbsp;
&nbsp;- Use an iRule to select a separate pool if the VS default pool is down.  You'd use [active_members [LB::server pool]] == 0 to check if the default pool is down and the pool command to select a second pool. &nbsp;
&nbsp;- Use an iRule to perform the same check of the VS default pool, but send static content from the iRule itself using HTTP::respond. &nbsp;
&nbsp; If you have questions on any of these options, reply back and we can give you more details and/or links. &nbsp;
&nbsp; Aaron

jeff_44423 · Answer

Thanks. I think i'm going to try the priority pool members first. Thx

will_ · Answer

Following on with this logic. What if you did have a GTM in front of the LTM. The GTM sees all the nodes down (via iQuery) does not resolve to the VIP on the LTM and the user never gets the "sorry page".  
&nbsp; Thoughts on possible resolution? We were thinking last-resort-pool. The question is can you use the origin pool to force GTM to resolve and send the client to the LTM where the "sorry page"  is served up. 
&nbsp;  
&nbsp; Thanks, 
&nbsp; Will

jeff_44423 · Answer

Hi wdoyle, 
&nbsp;  
&nbsp; Just to give you feedback on what i did. So in my orginal pool i had 3 members. I then added a newer member to the same pool that only served up the maint. page BUT with a lower priority. The result is the 3 org. server always get used because they have a higher priority until all 3 are down. Then it will roll to my 4 server in the same pool. If your GTM (WIP) is reaching your LTM via iquery (VIP) and the 1st 3 servers fail it should still use the last 4th member since it's in the same pool. Attached is the link i used. response from The Bhattman on the top of the page. 
&nbsp;  
&nbsp; https://devcentral.f5.com/Community/GroupDetails/tabid/1082223/asg/52/aft/1172236/showtab/groupforums/Default.aspx 
&nbsp;  
&nbsp;  
&nbsp; BTW, Aaron,  my post back in 2/14 worked for 80 and 443 traffic perfectly. Thanks again.

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POOL OF LAST RESORT

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