Subject: Re: DRBD8: Fencing and outdate-peer handler getting called multiple times - msg#00005

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Re: larger than 4tb volume status

Am Dienstag, 7. November 2006 00:44 schrieb Federico Grau: > Hello, > > What is the plan for supporting volumes larger than 4terabytes, I don't see > any mention to that in the svn ROADMAP file. > Our current business model has two tree steams of revenue in the DRBD area * Support contracts * Doing projects, workshops and consulting in the DRBD area * Selling DRBD+ licenses Wile keeping the basis technology open source... In case you have two times 4TB of storage you spent already quite some money on hard disks. In that case we expect you to support DRBD with buying a DRBD+ license. See http://www.linbit.com/en/drbd/drbd-plus/2/ -Phil -- : Dipl-Ing Philipp Reisner Tel +43-1-8178292-50 : : LINBIT Information Technologies GmbH Fax +43-1-8178292-82 : : Schönbrunnerstr 244, 1120 Vienna, Austria http://www.linbit.com :

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Re: DRBD8: Split-brain false positive on Primary/primary potential patch

Am Dienstag, 7. November 2006 00:47 schrieb Montrose, Ernest: > When running Primary/Primary if the Heartbeat connection goes down when > we recover we always split brain. Simon had an idea which I have > implemented. He is on vacation so this may not reflect his exact idea. > > Essentially with this change, we do not create a new current UUID on the > node unless I/O is seen. This prevent Split-Brain mitigation when both > nodes are primary but only one node is originating I/O and never the > other. He is only stand-by in that case. > > Take a look and let me know. Hi Ernest, I understand your reasoning, I see the patch, which I guess does what you expect of it. I do not want to do it that way for the following reasons: * It is only applicable in case you are using a 1-node filesystem on a primary-primary DRBD cluster. * I do not want users to do this. Because with this setup it is easily possible to mount the FS on both nodes concurrently. I want to protect the from themselfs ;) * Users using a 1-node filesystem should use DRBD withe primary and secondary role. * I rather want to fix DRBD's split brain recovery methods to deal with a cluster crash of a primary-primary cluster (actually this is item 41 in the ROADMAP file) I have a few hours time today, I will work on this today... -Phil -- : Dipl-Ing Philipp Reisner Tel +43-1-8178292-50 : : LINBIT Information Technologies GmbH Fax +43-1-8178292-82 : : Schönbrunnerstr 244, 1120 Vienna, Austria http://www.linbit.com :

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DRBD8: Fencing and outdate-peer handler getting called multiple times

Hi all, I have submitted this issue before, sorry for resubmit. Essentially, on the primary node if I do an ifdown on the heartbeat interface and I have fencing enable to say "resource-only" then on the primary node the outdate-peer script gets called twice. Once for state Disconnecting, and the other for state Networkfailure. I also notice that if on a node that is primary, I issue a "drbdadm secondary r0" the outdate-peer script gets called again from drbd_set_role() this time. What is the exact policy for the outdate-peer script? Thanks, EM--

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RE: DRBD8: Fencing and outdate-peer handler getting called multiple times

Phil, My outdate-peer handler simply says "echo /deve/drbd0: Running handler for outdate-peer >>/tmp/drbdio.log" And that log file is populated and created so I can only assume that did indicate success. In this case success being an exit status of 0. Thanks, EM-- -----Original Message----- From: Philipp Reisner [mailto:philipp.reisner-63ez5xqkn6DQT0dZR+AlfA@xxxxxxxxxxxxxxxx] Sent: Thursday, November 16, 2006 3:54 AM To: drbd-dev-63ez5xqkn6DQT0dZR+AlfA@xxxxxxxxxxxxxxxx Cc: Montrose, Ernest Subject: Re: [Drbd-dev] DRBD8: Fencing and outdate-peer handler getting called multiple times Am Dienstag, 7. November 2006 00:16 schrieb Montrose, Ernest: > Hi all, > I have submitted this issue before, sorry for resubmit. Essentially, on > the primary node if I do an ifdown on the heartbeat interface and I have > fencing enable to say "resource-only" then on the primary node the > outdate-peer script gets called twice. Once for state Disconnecting, > and the other for state Networkfailure. Maybe the return code of the outdate-peer handler did not indicated success. > > I also notice that if on a node that is primary, I issue a "drbdadm > secondary r0" the outdate-peer script gets called again from > drbd_set_role() this time. Maybe the return code of the outdate-peer handler did not indicated success. > What is the exact policy for the outdate-peer script? This is the section of the ROADMAP file, that describes how it *should* work: 7 Handle split brain situations; Support IO fencing; New commands: drbdadm outdate r0 When the device is configured this works via an ioctl() call. In the other case it modifies the meta data directly by calling drbdmeta. remove option: on-disconnect New meta-data flag: "Outdated" introduce: disk { fencing [ dont-care | resource-only | resource-and-stonith ]; } handlers { outdate-peer "some script"; } If the disk state of the peer is unknown, drbd calls this handler (yes a call to userspace from kernel space). The handler's returncodes are: 3 -> peer is inconsistent 4 -> peer is outdated (this handler outdated it) [ resource fencing ] 5 -> peer was down / unreachable 6 -> peer is primary 7 -> peer got stonithed [ node fencing ] Let us assume that we have two boxes (N1 and N2) and that these two boxes are connected by two networks (net and cnet [ clinets'-net ]). Net is used by DRBD, while heartbeat uses both, net and cnet I know that you are talking about fencing by STONITH, but DRBD is not limited to that. Here comes my understanding of how resource fencing should works with DRBDv8 : N1 net N2 P/S --- S/P everything up and running. P/? - - S/? network breaks ; N1 freezes IO P/? - - S/? N1 fences N2: In the STONITH case: turn off N2. In the resource fencing case: N1 asks N2 to fence itself from the storage via cnet. HB calls "drbdadm outdate r0" on N2. N2 replies to N1 that fencing is done via cnet. The outdate-peer script on N1 returns sucess to DRBD. P/D - - S/? N1 thaws IO N2 got the the "Outdated" flag set in its meta-data, by the outdate command. The fencing is set to resource-only enables this behaviour. In the resource-only case the outdate-peer handler should have a return value of 3, 4, 5 or 6, but should not return 7. In case "fencing" is set to "resource-and-stonith", all IO operations get immediately frozen (even all currently outstanding IO operations will not finish) upon loss of connection. Then the "outdate-peer" handler is started. In this configuration the outdate peer handler might return any of the documented return values. When the outdate-peer handler returns IO is resumed. Notes: * Why do we need to freeze IO in the "resource-and-stonith" case: Stonith protects you when all communication pathes fail. In that case both (isolated) nodes try to stonith each other. If the current primary would continue to allow IO it could accept transactions, but could get stonithed by the currently secondary node. -> Therefore others could see commited transactions that would be gone after the successfull stonith operation. * The outedate peer handler also gets called if an unconnected secondary wants to become primary. In other words it only may become primary when it knows that the peer is outdated/inconsistent. * We need to store the fact that the peer is outdated/inconsistent in the meta-data. To allow an stand allone primary to be rebooted. Does this answer your question ? -Phil -- : Dipl-Ing Philipp Reisner Tel +43-1-8178292-50 : : LINBIT Information Technologies GmbH Fax +43-1-8178292-82 : : Schönbrunnerstr 244, 1120 Vienna, Austria http://www.linbit.com :