SDS Mach 11
Question (not a fault): in a MACH11 cluster using Shared Disk Secondaries, how does Informix spread load across servers, and what happens if two clients update the same row? Answers: the Connection Manager balances only new connections (weighing available CPU cycles/load, also used to pick a failover target); once connected, a client stays on that server and is never migrated. All secondaries forward writes to the primary, so concurrent updates to a row behave exactly as if all users were on the primary, though slower network links can lose the race for the lock.
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When you are using SDS with Mach 11, how does Informix balance the load across multiple pieces of hardware that are all using SDS to share a disk? I assume through connection manager, but I would like to understand the logic of how it determines how to send a transaction. Also, if two clients are trying to write to the same row at once, how is that handled? Is it the same as when you have hot-hot HDR - where only one of the servers does all the writing? Thanks! Kate Tomchik [ kate@iiug.org ] www.iiug.org International Informix Users Group Board of Directors A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila. Mitch Ratliffe
kate said: > When you are using SDS with Mach 11, how does Informix balance the load > across multiple pieces of hardware that are all using SDS to share a disk? > I assume through connection manager, but I would like to understand the > logic of how it determines how to send a transaction. I don't think it manages transaction load, it manages connection load. In other words, once you are connected to Box A, you stay connected to Box A. > Also, if two clients are trying to write to the same row at once, how is > that handled? Is it the same as when you have hot-hot HDR - where only one > of the servers does all the writing? It is the same. -- Bye now, Obnoxio http://obotheclown.blogspot.com/ -- This message has been scanned for viruses and dangerous content by OpenProtect(http://www.openprotect.com), and is believed to be clean.
Connection manager would do the load balancing for new connection requests. Once application connects to the server, connection manager is out of picture. Primary does all the writing in MACH11 cluster. - Nilesh - ids-bounces@iiug.org wrote on 09/16/2009 12:31:05 PM: > [image removed] > > SDS Mach 11 [17031] > > kate > > to: > > ids > > 09/16/2009 12:31 PM > > Sent by: > > ids-bounces@iiug.org > > Please respond to ids > > When you are using SDS with Mach 11, how does Informix balance the load > across multiple pieces of hardware that are all using SDS to share a disk? > I assume through connection manager, but I would like to understand the > logic of how it determines how to send a transaction. > > Also, if two clients are trying to write to the same row at once, how is > that handled? Is it the same as when you have hot-hot HDR - where only one > of the servers does all the writing? > > Thanks! > Kate Tomchik [ kate@iiug.org ] www.iiug.org > International Informix Users Group Board of Directors > > A computer lets you make more mistakes faster than any invention in human > history - with the possible exceptions of handguns and tequila. > Mitch Ratliffe > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. >
So is the connection made to the one with the least number of connections? No logic based on which CPU is busier or which one has the most available buffer space? Thanks! Kate Tomchik [ kate@iiug.org ] www.iiug.org International Informix Users Group Board of Directors A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila. Mitch Ratliffe ---------- Original Message ----------- From: "Obnoxio The Clown" <obnoxio@serendipita.com> To: ids@iiug.org Sent: Wed, 16 Sep 2009 13:46:42 -0400 (EDT) Subject: Re: SDS Mach 11 [17032] > kate said: > > When you are using SDS with Mach 11, how does Informix balance the load > > across multiple pieces of hardware that are all using SDS to share a disk? > > I assume through connection manager, but I would like to understand the > > logic of how it determines how to send a transaction. > > I don't think it manages transaction load, it manages connection > load. In other words, once you are connected to Box A, you stay > connected to Box A. > > > Also, if two clients are trying to write to the same row at once, how is > > that handled? Is it the same as when you have hot-hot HDR - where only one > > of the servers does all the writing? > > It is the same. > > -- > Bye now, > Obnoxio > > http://obotheclown.blogspot.com/ > > -- > This message has been scanned for viruses and > dangerous content by OpenProtect(http://www.openprotect.com), and is > believed to be clean. > > ***************************************************************************** ** Forum Note: Use "Reply" to post a response in the discussion forum. ------- End of Original Message -------
kate said: > So is the connection made to the one with the least number of connections? > No logic based on which CPU is busier or which one has the most available > buffer space? I think it does a connection load / busyness tradeoff. But that's only at connection time. It never re-evaluates it or migrates you elsewhere. -- Bye now, Obnoxio http://obotheclown.blogspot.com/ -- This message has been scanned for viruses and dangerous content by OpenProtect(http://www.openprotect.com), and is believed to be clean.
It monitors the potential available cpu cycles in making the decision. = "kate" = <kate@iiug.org> = Sent by: = To ids-bounces@iiug. ids@iiug.org = org = cc = Subj= ect 09/16/2009 01:00 Re: SDS Mach 11 [17034] = PM = = = Please respond to = ids@iiug.org = = = So is the connection made to the one with the least number of connectio= ns? No logic based on which CPU is busier or which one has the most availab= le buffer space? Thanks! Kate Tomchik [ kate@iiug.org ] www.iiug.org International Informix Users Group Board of Directors A computer lets you make more mistakes faster than any invention in hum= an history - with the possible exceptions of handguns and tequila. Mitch Ratliffe ---------- Original Message ----------- From: "Obnoxio The Clown" <obnoxio@serendipita.com> To: ids@iiug.org Sent: Wed, 16 Sep 2009 13:46:42 -0400 (EDT) Subject: Re: SDS Mach 11 [17032] > kate said: > > When you are using SDS with Mach 11, how does Informix balance the = load > > across multiple pieces of hardware that are all using SDS to share = a disk? > > I assume through connection manager, but I would like to understand= the > > logic of how it determines how to send a transaction. > > I don't think it manages transaction load, it manages connection > load. In other words, once you are connected to Box A, you stay > connected to Box A. > > > Also, if two clients are trying to write to the same row at once, h= ow is > > that handled? Is it the same as when you have hot-hot HDR - where o= nly one > > of the servers does all the writing? > > It is the same. > > -- > Bye now, > Obnoxio > > http://obotheclown.blogspot.com/ > > -- > This message has been scanned for viruses and > dangerous content by OpenProtect(http://www.openprotect.com), and is > believed to be clean. > > ***********************************************************************= ****** ** Forum Note: Use "Reply" to post a response in the discussion forum. ------- End of Original Message ------- ***********************************************************************= ******** Forum Note: Use "Reply" to post a response in the discussion forum. =
Connections are made based on CPU Load but as OTC said, the Connection Manager only load balances connections (and uses load to determine which secondary should take over if the primary fails) once you are connected to a server you no longer talk to the connection manager and remain connected to the same server unless it goes offline. On your other question, yes, all MACH11 secondaries pass writes through to the primary to be processed, so multiple users modifying the same row have the same priorities and results as if they were all connected to the primary. In a true simultaneous update, connections to secondaries separated from the primary by network segments with slower connectivity or higher intra network traffic may be at a disadvantage to win the race to lock other users out, but that's always been true. Art Art S. Kagel Oninit (www.oninit.com) IIUG Board of Directors (art@iiug.org) Disclaimer: Please keep in mind that my own opinions are my own opinions and do not reflect on my employer, Oninit, the IIUG, nor any other organization with which I am associated either explicitly or implicitly. Neither do those opinions reflect those of other individuals affiliated with any entity with which I am affiliated nor those of the entities themselves. On Wed, Sep 16, 2009 at 2:00 PM, kate <kate@iiug.org> wrote: > So is the connection made to the one with the least number of connections? > No logic based on which CPU is busier or which one has the most available > buffer space? > > Thanks! > Kate Tomchik [ kate@iiug.org ] www.iiug.org > International Informix Users Group Board of Directors > > A computer lets you make more mistakes faster than any invention in human > history - with the possible exceptions of handguns and tequila. > Mitch Ratliffe > > ---------- Original Message ----------- > From: "Obnoxio The Clown" <obnoxio@serendipita.com> > To: ids@iiug.org > Sent: Wed, 16 Sep 2009 13:46:42 -0400 (EDT) > Subject: Re: SDS Mach 11 [17032] > > > kate said: > > > When you are using SDS with Mach 11, how does Informix balance the load > > > across multiple pieces of hardware that are all using SDS to share a > disk? > > > I assume through connection manager, but I would like to understand the > > > logic of how it determines how to send a transaction. > > > > I don't think it manages transaction load, it manages connection > > load. In other words, once you are connected to Box A, you stay > > connected to Box A. > > > > > Also, if two clients are trying to write to the same row at once, how > is > > > that handled? Is it the same as when you have hot-hot HDR - where only > one > > > of the servers does all the writing? > > > > It is the same. > > > > -- > > Bye now, > > Obnoxio > > > > http://obotheclown.blogspot.com/ > > > > -- > > This message has been scanned for viruses and > > dangerous content by OpenProtect(http://www.openprotect.com), and is > > believed to be clean. > > > > > > ***************************************************************************** > ** Forum Note: Use "Reply" to post a response in the discussion forum. > ------- End of Original Message ------- > > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. > > --0015174ff09429bfa40473b74a3c