Hi Mahesh,
Please see my answers below with [NhatPham5] Best regards, Nhat Pham From: A V Mahesh [mailto:mahesh.va...@oracle.com] Sent: Friday, February 26, 2016 11:17 AM To: Nhat Pham <nhat.p...@dektech.com.au>; 'Anders Widell' <anders.wid...@ericsson.com> Cc: opensaf-devel@lists.sourceforge.net; 'Beatriz Brandao' <beatriz.bran...@ericsson.com>; 'Minh Chau H' <minh.c...@dektech.com.au> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] Hi Nhat Pham, >>[NhatPham4] To be more correct, the application will get SA_AIS_ERR_BAD_HANDLE when trying to access the lost checkpoint because all data was destroyed. >>[AndersW4] If this is a problem we could re-create the checkpoint with no sections in it. Even I come across this approach , instead of destroying the checkpoint information (current patch doing) from CPND of payloads and returning the SA_AIS_ERR_BAD_HANDLE applcation on PL`s in the NEW patch V3 check the possibility of re-cremating the checkpoint with sections ( you can send this data from PL to SC up on CPD up) . [NhatPham5] The "all data" here I means the checkpoint node information in database controlled by cpnd (not the replica). In this case, all replicas were lost. How can the checkpoint be re-created with sections? For other cases where the checkpoint replicas survive, the checkpoint is restored when the SC is up again. Ex: A checkpoint is created on a PL. There are 3 replicas created on SCs and PL. The headless state happens. After the SC is up, the checkpoint is recovered. -AVM On 2/26/2016 8:11 AM, Nhat Pham wrote: Hi, Please see my comment below with [NhatPham4] Best regards, Nhat Pham From: Anders Widell [mailto:anders.wid...@ericsson.com] Sent: Thursday, February 25, 2016 9:25 PM To: A V Mahesh <mailto:mahesh.va...@oracle.com> <mahesh.va...@oracle.com>; Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au> Cc: opensaf-devel@lists.sourceforge.net <mailto:opensaf-devel@lists.sourceforge.net> ; 'Beatriz Brandao' <mailto:beatriz.bran...@ericsson.com> <beatriz.bran...@ericsson.com>; 'Minh Chau H' <mailto:minh.c...@dektech.com.au> <minh.c...@dektech.com.au> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] Hi! See my comments inline, marked [AndersW4]. regards, Anders Widell On 02/25/2016 05:26 AM, A V Mahesh wrote: Hi Nhat Pham, Please see my comment below. -AVM On 2/25/2016 7:54 AM, Nhat Pham wrote: Hi Mahesh, Would you agree with the comment below? To summarize, following are the comment so far: Comment 1: This functionality should be under checks if Hydra configuration is enabled in IMM attrName = const_cast<SaImmAttrNameT>("scAbsenceAllowed"). Action: The code will be updated accordingly. [AndersW4] Just a question here: is this really needed? If the code is already 100% backwards compatible when the headless feature is disabled, what would be the point of reading the configuration and taking different paths in the code depending on it? Maybe the code is not 100% backwards compatible and then I agree that we need to read the configuration. The reason why I am asking is that I had the impression that the code would only cause different behaviour in the cases where both system controllers die at the same time, and this cannot happen when the headless feature is disabled (or rather: it can happen, but it would trigger an immediate cluster restart so any difference in behaviour after that point is irrelevant). [NhatPham4] The code is backwards compatible when the headless feature is disable. For V2 patch, cpnd will update cpd with recoverable checkpoint data when SC is up after headless state.(From implementation point of view) In current system if the headless feature is disable, whole cluster reboots. Thus all data is destroyed. For V2 patch + checking scAbsenceAllowed, cpnd destroys all the checkpoint data (as original implementation). (From implementation point of view) In current system if the headless feature is disable, whole cluster reboots. Thus all data is destroyed. So if you ask if the checking is really needed in current situation. The answer is not really. This checking is just to make sure that all checkpoint data is destroyed in case headless feature is disable. How do you think? Comment 2: To keep the scope of CPSV service as non-collocated checkpoint creation NOT_SUPPORTED , if cluster is running with IMMSV_SC_ABSENCE_ALLOWED ( headless state configuration enabled at the time of cluster startup currently it is not configurable , so there no chance of run-time configuration change ). Action: No change in code. The CPSV still keep supporting non-collocated checkpoint even if IMMSV_SC_ABSENCE_ALLOWED is enable. >>[AndersW3] No, I think we ought to support non-colocated checkpoints also when IMMSV_SC_ABSENCE_ALLOWED is set. The fact that we have "system controllers" is an implementation detail of OpenSAF. I don't think the CKPT SAF specification implies that >>non-colocated checkpoints must be fully replicated on all the nodes in the cluster, and thus we must have the possibility that all replicas are lost. It is not clear exactly what to expect from the APIs when this happens, but you could handle it in a similar way as the case >> when all sections have been automatically deleted by the checkpoint service because the sections have expired. [AVM] I am not in agreement with both comments , we can not handle it in a similar to sections expiration case hear , in case of sections expiration checkpoint replica still exist only section deleted [AndersW4] If this is a problem we could re-create the checkpoint with no sections in it. CPSV specification says if two replicas exist ( in our case Only on SC`s) at a certain point in time, and the nodes hosting both of these replicas is administratively taken out of service, the Checkpoint Service should allocate another replica on another node while this node is not available please check section `3.1.7.2 Non-Collocated Checkpoints` of cpsv specification . [AndersW4] The spec actually says "may" rather than "should" in this section. And the purpose of allocating another replica is to "enhance the availability of checkpoints". When I read this section, I think it is quite clear that the spec does not perceive non-colocated checkpoints as guaranteed to preserve data in the case of node failures: "The Checkpoint Service may create replicas other than the ones that may be created when opening a checkpoint. These other replicas can be useful to enhance the availability of checkpoints. For example, if two replicas exist at a certain point in time, and the node hosting one of these replicas is administratively taken out of service, the Checkpoint Service may allocate another replica on another node while this node is not available." So, data can be lost due to (multiple) node failures. There are two other cases where data is lost: automatic deletion of the entire checkpoint if it has not been opened by any process for the duration of the retention time, and automatic deletion of sections within a checkpoint when the sections reach their expiration times. The APIs specify the return code SA_AIS_ERR_NOT_EXIST to signal that a specific section, or the entire checkpoint, doesn't exist. Thus, there support in the API for reporting loss of checkpoint data (whatever the reason of the loss may be). If the headless feature is disabled, we cannot lose non-colocated checkpoints due to node failures, but when the headless feature is enabled we can. For example, take a case of application on PL is in progress of writing to non-collocated checkpoint sections ( physical replica exist only on SC`s ) what will happen to application on PL ? , ok let us consider user agreed to loose the checkpoint and he what to recreated it , what will happen to cpnd DB on PL and the complexity involved in it (clean up) , and this will lead to lot of maintainability issues. [AndersW4] The thing that will happen (from an application's perspective) is that you will get the SA_AIS_ERR_NOT_EXIST error code from the CKPT API when trying to access the lost checkpoint. I don't know the complexity at the code level for implementing this, but isn't this already supported by the code which is out on review (Nhat, correct me if I am wrong)? [NhatPham4] To be more correct, the application will get SA_AIS_ERR_BAD_HANDLE when trying to access the lost checkpoint because all data was destroyed. But for opening the checkpoint (not creating), it will get SA_AIS_ERR_NOT_EXIST. On top of that CKPT SAF specification only says that non-collocated checkpoint and all its sections should survive if the Checkpoint Service running on cluster and replica is USER private data ( not Opensaf States ) , loosing any USER private data not acceptable . Comment 3: This is about case where checkpoint node director (cpnd) crashes during headless state. In this case the cpnd can't finish starting because it can't initialize CLM service. Then after time out, the AMF triggers a restart again. Finally, the node is rebooted. It is expected that this problem should not lead to a node reboot. Action: No change in code. This is the limitation of the system during headless state. [AVM] code changes required in CPSV CLM integration code need to be revisited to handle TRYAGAIN. If you agree with the summary above, I'll update code and send out the V3 for review. Best regards, Nhat Pham From: Anders Widell [mailto:anders.wid...@ericsson.com] Sent: Wednesday, February 24, 2016 9:26 PM To: Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au>; 'A V Mahesh' <mailto:mahesh.va...@oracle.com> <mahesh.va...@oracle.com> Cc: opensaf-devel@lists.sourceforge.net <mailto:opensaf-devel@lists.sourceforge.net> ; 'Beatriz Brandao' <mailto:beatriz.bran...@ericsson.com> <beatriz.bran...@ericsson.com>; 'Minh Chau H' <mailto:minh.c...@dektech.com.au> <minh.c...@dektech.com.au> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] See my comments inline, marked [AndersW3]. regards, Anders Widell On 02/24/2016 07:32 AM, Nhat Pham wrote: Hi Mahesh and Anders, Please see my comments below. Best regards, Nhat Pham From: A V Mahesh [mailto:mahesh.va...@oracle.com] Sent: Wednesday, February 24, 2016 11:06 AM To: Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au>; 'Anders Widell' <mailto:anders.wid...@ericsson.com> <anders.wid...@ericsson.com> Cc: opensaf-devel@lists.sourceforge.net <mailto:opensaf-devel@lists.sourceforge.net> ; 'Beatriz Brandao' <mailto:beatriz.bran...@ericsson.com> <beatriz.bran...@ericsson.com>; 'Minh Chau H' <mailto:minh.c...@dektech.com.au> <minh.c...@dektech.com.au> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] Hi Nhat Pham, If component ( CPND ) restart allows while Controllers absent , before requesting CLM going to change return value to SA_AIS_ERR_TRY_AGAIN , We need to get clarification from AMF guys on few things why because if CPND is on SA_AIS_ERR_TRY_AGAIN and component restart timeout then AMF will restart component again ( this become cyclic ) and after saAmfSGCompRestartMax configured value Node gose for reboot as next level escalation, in that case we may required changes in AMF as well, to not to act on component restart timeout in case of Controllers absent ( i am not sure it is deviation of AMF specification ) . [Nhat Pham] In headless state, I'm not sure about this either. @Anders: Would you have comments about this? [AndersW3] Ok, first of all I would like to point out that normally, the OpenSAF checkpoint node director should not crash. So we are talking about a situation where multiple faults have occurred: first both the active and the standby system controllers have died, and then shortly afterwards - before we have a new active system controller - the checkpoint node director also crashes. Sure, these may not be totally independent events, but still there are a lot of faults that have happened within a short period of time. We should test the node director and make sure it doesn't crash in this type of scenario. Now, let's consider the case where we have a fault in the node director that causes it to crash during the headless state. The general philosophy of the headless feature is that when things work fine - i.e. in the absence of fault - we should be able to continue running while the system controllers are absent. However, if a fault happens during the headless state, we may not be able to recover from the fault until there is an active system controller. AMF does provide support for restarting components, but as you have pointed out, the node director will be stuck in a TRY_AGAIN loop immediately after it has been restarted. So this means that if the node director crashes during the headless state, we have lost the checkpoint functionality on that node and we will not get it back until there is an active system controller. Other services like IMM will still work for a while, but AMF will as you say eventually escalate the checkpoint node director failure to a node restart and then the whole node is gone. The node will not come back until we have an active system controller. So to summarize: there is very limited support for recovering from faults that happen during the headless state. The full recovery will not happen until we have an active system controller. Please do incorporate current comments ( in design prospective ) and republish the patch , I will re-test V3 patch and provide review comments on function issue/bugs if I found any. One Important note , in the new patch let us not have any complexity of allowing non-collocated checkpoint creation and then documenting that in some scenario , non-collocated checkpoint replicas are recoverable , why because replica is USER private data ( not Opensaf States ) , loosing USER private data not acceptable . so let us keep the scope of CPSV service as non-collocated checkpoint creation NOT_SUPPORTED , if cluster is running with IMMSV_SC_ABSENCE_ALLOWED ( headless state configuration enabled at the time of cluster startup currently it is not configurable , so their no chance of run-time configuration change ). We can provide support for non-collocated in subsequent enhancements by having solution like replica on lower node ID PL will also created non-collocated ( max three riplicas in cluster regradless of where non-collocated is opened ). So for now, regardless of the heads (SC`s) status exist not exist CPSV should return SA_AIS_ERR_NOT_SUPPORTED in case of IMMSV_SC_ABSENCE_ALLOWED enabled cluster , and let us document it as well. [Nhat Pham] The patch is to limit loosing replicas and checkpoints in case of headless state. In case both replicas locate on SCs and they reboot, loosing checkpoint is unpreventable with current design after headless state. Even if we implement the proposal "max three riplicas in cluster regradless of where non-collocated is opened", there is still the case where the checkpoint is lost. Ex. The SCs and the PL which hosts the replica reboot same time. In case IMMSV_SC_ABSENCE_ALLOWED disable, if both SCs reboot, this leads whole cluster reboots. Then the checkpoint is lost. What I mean is there are cases where the checkpoint is lost. The point is what we can do to limit loosing data. For the proposal of reject creating non-collocated checkpoint in case of IMMSV_SC_ABSENCE_ALLOWED enabled, I think this will lead to in compatible problem. @Anders: How do you think about rejecting creating non-collocated checkpoint in case of IMMSV_SC_ABSENCE_ALLOWED enabled? [AndersW3] No, I think we ought to support non-colocated checkpoints also when IMMSV_SC_ABSENCE_ALLOWED is set. The fact that we have "system controllers" is an implementation detail of OpenSAF. I don't think the CKPT SAF specification implies that non-colocated checkpoints must be fully replicated on all the nodes in the cluster, and thus we must have the possibility that all replicas are lost. It is not clear exactly what to expect from the APIs when this happens, but you could handle it in a similar way as the case when all sections have been automatically deleted by the checkpoint service because the sections have expired. -AVM On 2/24/2016 6:51 AM, Nhat Pham wrote: Hi Mahesh, Do you have any further comments? Best regards, Nhat Pham From: A V Mahesh [mailto:mahesh.va...@oracle.com] Sent: Monday, February 22, 2016 10:37 AM To: Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au>; 'Anders Widell' <mailto:anders.wid...@ericsson.com> <anders.wid...@ericsson.com> Cc: opensaf-devel@lists.sourceforge.net <mailto:opensaf-devel@lists.sourceforge.net> ; 'Beatriz Brandao' <mailto:beatriz.bran...@ericsson.com> <beatriz.bran...@ericsson.com>; 'Minh Chau H' <mailto:minh.c...@dektech.com.au> <minh.c...@dektech.com.au> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] Hi, >>BTW, have you finished the review and test? I will finish by today. -AVM On 2/22/2016 7:48 AM, Nhat Pham wrote: Hi Mahesh and Anders, Please see my comment below. BTW, have you finished the review and test? Best regards, Nhat Pham From: A V Mahesh [mailto:mahesh.va...@oracle.com] Sent: Friday, February 19, 2016 2:28 PM To: Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au>; 'Anders Widell' <mailto:anders.wid...@ericsson.com> <anders.wid...@ericsson.com>; 'Minh Chau H' <mailto:minh.c...@dektech.com.au> <minh.c...@dektech.com.au> Cc: opensaf-devel@lists.sourceforge.net <mailto:opensaf-devel@lists.sourceforge.net> ; 'Beatriz Brandao' <mailto:beatriz.bran...@ericsson.com> <beatriz.bran...@ericsson.com> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] Hi Nhat Pham, On 2/19/2016 12:28 PM, Nhat Pham wrote: Could you please give more detailed information about steps to reproduce the problem below? Thanks. Don't see this as specific bug , we need to see the issue as CLM integrated service point of view , by considering Anders Widell explication about CLM application behavior during headless state we need to reintegrate CPND with CLM ( before this headless state feature no case of CPND existence in the obscene of CLMD , but now it is ). And this will be the consistent across the all services who integrated with CLM ( you may need some changes in CLM also ) [Nhat Pham] I think CLM should return SA_AIS_ERR_TRY_AGAIN in this case. @Anders. How would you think? To start with let us consider case CPND on payload restarted on PL during headless state and an application is in running on PL. [Nhat Pham] Regarding the CPND as CLM application, I'm not sure what it can do in this case. In case it restarts, it is monitored by AMF. If it blocks for too long, AMF will also trigger a node reboot. In my test case, the CPND get blocked by CLM. It doesn't get out of the saClmInitialize. How do you get the "ER cpnd clm init failed with return value:31"? Following is the cpnd trace. Feb 22 8:56:41.188122 osafckptnd [736:cpnd_init.c:0183] >> cpnd_lib_init Feb 22 8:56:41.188332 osafckptnd [736:cpnd_init.c:0412] >> cpnd_cb_db_init Feb 22 8:56:41.188600 osafckptnd [736:cpnd_init.c:0437] << cpnd_cb_db_init Feb 22 8:56:41.188778 osafckptnd [736:clma_api.c:0503] >> saClmInitialize Feb 22 8:56:41.188945 osafckptnd [736:clma_api.c:0593] >> clmainitialize Feb 22 8:56:41.190052 osafckptnd [736:clma_util.c:0100] >> clma_startup: clma_use_count: 0 Feb 22 8:56:41.190273 osafckptnd [736:clma_mds.c:1124] >> clma_mds_init Feb 22 8:56:41.190825 osafckptnd [736:clma_mds.c:1170] << clma_mds_init -AVM On 2/19/2016 12:28 PM, Nhat Pham wrote: Hi Mahesh, Could you please give more detailed information about steps to reproduce the problem below? Thanks. Best regards, Nhat Pham From: A V Mahesh [mailto:mahesh.va...@oracle.com] Sent: Friday, February 19, 2016 1:06 PM To: Anders Widell <mailto:anders.wid...@ericsson.com> <anders.wid...@ericsson.com>; Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au>; 'Minh Chau H' <mailto:minh.c...@dektech.com.au> <minh.c...@dektech.com.au> Cc: opensaf-devel@lists.sourceforge.net <mailto:opensaf-devel@lists.sourceforge.net> ; 'Beatriz Brandao' <mailto:beatriz.bran...@ericsson.com> <beatriz.bran...@ericsson.com> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] Hi Anders Widell, Thanks for the detailed explanation about CLM during headless state. HI Nhat Pham , Comment : 3 Please see below the problem I was interpreted now I seeing it during CLMD obscene ( during headless state ), so now CPND/CLMA need to to address below case , currently cpnd clm init failed with return value: SA_AIS_ERR_UNAVAILABLE but should be SA_AIS_ERR_TRY_AGAIN ================================================== Feb 19 11:18:28 PL-4 osafimmnd[5422]: NO NODE STATE-> IMM_NODE_FULLY_AVAILABLE 17418 Feb 19 11:18:28 PL-4 osafimmloadd: NO Sync ending normally Feb 19 11:18:28 PL-4 osafimmnd[5422]: NO Epoch set to 9 in ImmModel Feb 19 11:18:28 PL-4 cpsv_app: IN Received PROC_STALE_CLIENTS Feb 19 11:18:28 PL-4 osafimmnd[5422]: NO Implementer connected: 42 (MsgQueueService132111) <108, 2040f> Feb 19 11:18:28 PL-4 osafimmnd[5422]: NO Implementer connected: 43 (MsgQueueService131855) <0, 2030f> Feb 19 11:18:28 PL-4 osafimmnd[5422]: NO Implementer connected: 44 (safLogService) <0, 2010f> Feb 19 11:18:28 PL-4 osafimmnd[5422]: NO SERVER STATE: IMM_SERVER_SYNC_SERVER --> IMM_SERVER_READY Feb 19 11:18:28 PL-4 osafimmnd[5422]: NO Implementer connected: 45 (safClmService) <0, 2010f> Feb 19 11:18:28 PL-4 osafckptnd[7718]: ER cpnd clm init failed with return value:31 Feb 19 11:18:28 PL-4 osafckptnd[7718]: ER cpnd init failed Feb 19 11:18:28 PL-4 osafckptnd[7718]: ER cpnd_lib_req FAILED Feb 19 11:18:28 PL-4 osafckptnd[7718]: __init_cpnd() failed Feb 19 11:18:28 PL-4 osafclmna[5432]: NO safNode=PL-4,safCluster=myClmCluster Joined cluster, nodeid=2040f Feb 19 11:18:28 PL-4 osafamfnd[5441]: NO AVD NEW_ACTIVE, adest:1 Feb 19 11:18:28 PL-4 osafamfnd[5441]: NO Sending node up due to NCSMDS_NEW_ACTIVE Feb 19 11:18:28 PL-4 osafamfnd[5441]: NO 1 SISU states sent Feb 19 11:18:28 PL-4 osafamfnd[5441]: NO 1 SU states sent Feb 19 11:18:28 PL-4 osafamfnd[5441]: NO 7 CSICOMP states synced Feb 19 11:18:28 PL-4 osafamfnd[5441]: NO 7 SU states sent Feb 19 11:18:28 PL-4 osafimmnd[5422]: NO Implementer connected: 46 (safAmfService) <0, 2010f> Feb 19 11:18:30 PL-4 osafamfnd[5441]: NO 'safSu=PL-4,safSg=NoRed,safApp=OpenSAF' Component or SU restart probation timer expired Feb 19 11:18:35 PL-4 osafamfnd[5441]: NO Instantiation of 'safComp=CPND,safSu=PL-4,safSg=NoRed,safApp=OpenSAF' failed Feb 19 11:18:35 PL-4 osafamfnd[5441]: NO Reason: component registration timer expired Feb 19 11:18:35 PL-4 osafamfnd[5441]: WA 'safComp=CPND,safSu=PL-4,safSg=NoRed,safApp=OpenSAF' Presence State RESTARTING => INSTANTIATION_FAILED Feb 19 11:18:35 PL-4 osafamfnd[5441]: NO Component Failover trigerred for 'safSu=PL-4,safSg=NoRed,safApp=OpenSAF': Failed component: 'safComp=CPND,safSu=PL-4,safSg=NoRed,safApp=OpenSAF' Feb 19 11:18:35 PL-4 osafamfnd[5441]: ER 'safComp=CPND,safSu=PL-4,safSg=NoRed,safApp=OpenSAF'got Inst failed Feb 19 11:18:35 PL-4 osafamfnd[5441]: Rebooting OpenSAF NodeId = 132111 EE Name = , Reason: NCS component Instantiation failed, OwnNodeId = 132111, SupervisionTime = 60 Feb 19 11:18:36 PL-4 opensaf_reboot: Rebooting local node; timeout=60 Feb 19 11:18:39 PL-4 kernel: [ 4877.338518] md: stopping all md devices. ================================================== -AVM On 2/15/2016 5:11 PM, Anders Widell wrote: Hi! Please find my answer inline, marked [AndersW]. regards, Anders Widell On 02/15/2016 10:38 AM, Nhat Pham wrote: Hi Mahesh, It's good. Thank you. :) [AVM] Up on rejoining of the SC`s The replica should be re-created regardless of another application opens it on PL4. ( Note : this comment is based on your explanation have not yet reviewed/tested , currently i am struggling with SC`s not rejoining after headless state , i can provide you more on this once i complte my review/testing) [Nhat] To make cloud resilience works, you need the patches from other services (log, amf, clm, ntf). @Minh: I heard that you created tar file which includes all patches. Could you please send it to Mahesh? Thanks [AVM] I understand that , before I comment more on this please allow me to understand I am not still not very clear of the headless design in detail. For example cluster membership of PL`s during headless state , In the absence of SC`s (CLMD) dose the PLs is considered as cluster nodes or not (cluster membership) ? [Nhat] I don't know much about this. @ Anders: Could you please have comment about this? Thanks [AndersW] First of all, keep in mind that the "headless" state should ideally not last a very long time. Once we have the spare SC feature in place (ticket [#79]), a new SC should become active within a matter of a few seconds after we have lost both the active and the standby SC. I think you should view the state of the cluster in the headless state in the same way as you view the state of the cluster during a failover between the active and the standby SC. Imagine that the active SC dies. It takes the standby SC 1.5 seconds to detect the failure of the active SC (this is due to the TIPC timeout). If you have configured the PROMOTE_ACTIVE_TIMER, there is an additional delay before the standby takes over as active. What is the state of the cluster during the time after the active SC failed and before the standby takes over? The state of the cluster while it is headless is very similar. The difference is that this state may last a little bit longer (though not more than a few seconds, until one of the spare SCs becomes active). Another difference is that we may have lost some state. With a "perfect" implementation of the headless feature we should not lose any state at all, but with the current set of patches we do lose state. So specifically if we talk about cluster membership and ask the question: is a particular PL a member of the cluster or not during the headless state? Well, if you ask CLM about this during the headless state, then you will not know - because CLM doesn't provide any service during the headless state. If you keep retrying you query to CLM, you will eventually get an answer - but you will not get this answer until there is an active SC again and we have exited the headless state. When viewed in this way, the answer to the question about a node's membership is undefined during the headless state, since CLM will not provide you with any answer until there is an active SC. However, if you asked CLM about the node's cluster membership status before the cluster went headless, you probably saved a cached copy of the cluster membership state. Maybe you also installed a CLM track callback and intend to update this cached copy every time the cluster membership status changes. The question then is: can you continue using this cached copy of the cluster membership state during the headless state? The answer is YES: since CLM doesn't provide any service during the headless state, it also means that the cluster membership view cannot change during this time. Nodes can of course reboot or die, but CLM will not notice and hence the cluster view will not be updated. You can argue that this is bad because the cluster view doesn't reflect reality, but notice that this will always be the case. We can never propagate information instantaneously, and detection of node failures will take 1.5 seconds due to the TIPC timeout. You can never be sure that a node is alive at this very moment just because CLM tells you that it is a member of the cluster. If we are unfortunate enough to lose both system controller nodes simultaneously, updates to the cluster membership view will be delayed a few seconds longer than usual. Best regards, Nhat Pham -----Original Message----- From: A V Mahesh [mailto:mahesh.va...@oracle.com] Sent: Monday, February 15, 2016 11:19 AM To: Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au>; anders.wid...@ericsson.com <mailto:anders.wid...@ericsson.com> Cc: opensaf-devel@lists.sourceforge.net <mailto:opensaf-devel@lists.sourceforge.net> ; 'Beatriz Brandao' <mailto:beatriz.bran...@ericsson.com> <beatriz.bran...@ericsson.com> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] Hi Nhat Pham, How is your holiday went Please find my comments below On 2/15/2016 8:43 AM, Nhat Pham wrote: Hi Mahesh, For the comment 1, the patch will be updated accordingly. [AVM] Please hold , I will provide more comments in this week , so we can have consolidated V3 For the comment 2, I think the CKPT service will not be backward compatible if the scAbsenceAllowed is true. The client can't create non-collocated checkpoint on SCs. Furthermore, this solution only protects the CKPT service from the case "The non-collocated checkpoint is created on a SC" there are still the cases where the replicas are completely lost. Ex: - The non-collocated checkpoint created on a PL. The PL reboots. Both replicas now locate on SCs. Then, headless state happens. All replicas are lost. - The non-collocated checkpoint has active replica locating on a PL and this PL restarts during headless state - The non-collocated checkpoint is created on PL3. This checkpoint is also opened on PL4. Then SCs and PL3 reboot. [AVM] Up on rejoining of the SC`s The replica should be re-created regardless of another application opens it on PL4. ( Note : this comment is based on your explanation have not yet reviewed/tested , currently i am struggling with SC`s not rejoining after headless state , i can provide you more on this once i complte my review/testing) In this case, all replicas are lost and the client has to create it again. In case multiple nodes (which including SCs) reboot, losing replicas is unpreventable. The patch is to recover the checkpoints in possible cases. How do you think? [AVM] I understand that , before I comment more on this please allow me to understand I am not still not very clear of the headless design in detail. For example cluster membership of PL`s during headless state , In the absence of SC`s (CLMD) dose the PLs is considered as cluster nodes or not (cluster membership) ? - if not consider as NON cluster nodes Checkpoint Service API should leverage the SA Forum Cluster Membership Service and API's can fail with SA_AIS_ERR_UNAVAILABLE - if considers as cluster nodes we need to follow all the defined rules which are defined in SAI-AIS-CKPT-B.02.02 specification so give me some more time to review it completely , so that we can have consolidated patch V3 -AVM Best regards, Nhat Pham -----Original Message----- From: A V Mahesh [mailto:mahesh.va...@oracle.com] Sent: Friday, February 12, 2016 11:10 AM To: Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au>; anders.wid...@ericsson.com <mailto:anders.wid...@ericsson.com> Cc: opensaf-devel@lists.sourceforge.net <mailto:opensaf-devel@lists.sourceforge.net> ; Beatriz Brandao <mailto:beatriz.bran...@ericsson.com> <beatriz.bran...@ericsson.com> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] Comment 2 : After incorporating the comment one all the Limitations should be prevented based on Hydra configuration is enabled in IMM status. Foe example : if some application is trying to create non-collocated checkpoint active replica getting generated/locating on SC then ,regardless of the heads (SC`s) status exist not exist should return SA_AIS_ERR_NOT_SUPPORTED In other words, rather that allowing to created non-collocated checkpoint when heads(SC`s) are exit , and non-collocated checkpoint getting unrecoverable after heads(SC`s) rejoins. ====================================================================== ======================= Limitation: The CKPT service doesn't support recovering checkpoints in following cases: . The checkpoint which is unlinked before headless. . The non-collocated checkpoint has active replica locating on SC. . The non-collocated checkpoint has active replica locating on a PL and this PL restarts during headless state. In this cases, the checkpoint replica is destroyed. The fault code SA_AIS_ERR_BAD_HANDLE is returned when the client accesses the checkpoint in these cases. The client must re-open the checkpoint. ====================================================================== ======================= -AVM On 2/11/2016 12:52 PM, A V Mahesh wrote: Hi, I jut starred reviewing patch , I will be giving comments as soon as I crossover any , to save some time. Comment 1 : This functionality should be under checks if Hydra configuration is enabled in IMM attrName = const_cast<SaImmAttrNameT>("scAbsenceAllowed") Please see example how LOG/AMF services implemented it. -AVM On 1/29/2016 1:02 PM, Nhat Pham wrote: Hi Mahesh, As described in the README, the CKPT service returns SA_AIS_ERR_TRY_AGAIN fault code in this case. I guess it's same for other services. @Anders: Could you please confirm this? Best regards, Nhat Pham -----Original Message----- From: A V Mahesh [mailto:mahesh.va...@oracle.com] Sent: Friday, January 29, 2016 2:11 PM To: Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au>; anders.wid...@ericsson.com <mailto:anders.wid...@ericsson.com> Cc: opensaf-devel@lists.sourceforge.net <mailto:opensaf-devel@lists.sourceforge.net> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] Hi, On 1/29/2016 11:45 AM, Nhat Pham wrote: - The behavior of application will be consistent with other saf services like imm/amf behavior during headless state. [Nhat] I'm not clear what you mean about "consistent"? In the obscene of Director (SC's) , what is expected return values of SAF API should ( all services ) , which are not in aposition to provide service at that moment. I think all services should return same SAF ERRS., I thinks currently we don't have it , may be Anders Widel will help us. -AVM On 1/29/2016 11:45 AM, Nhat Pham wrote: Hi Mahesh, Please see the attachment for the README. Let me know if there is any more information required. Regarding your comments: - during headless state applications may behave like during CPND restart case [Nhat] Headless state and CPND restart are different events. Thus, the behavior is different. Headless state is a case where both SCs go down. - The behavior of application will be consistent with other saf services like imm/amf behavior during headless state. [Nhat] I'm not clear what you mean about "consistent"? Best regards, Nhat Pham -----Original Message----- From: A V Mahesh [mailto:mahesh.va...@oracle.com] Sent: Friday, January 29, 2016 11:12 AM To: Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au>; anders.wid...@ericsson.com <mailto:anders.wid...@ericsson.com> Cc: opensaf-devel@lists.sourceforge.net <mailto:opensaf-devel@lists.sourceforge.net> Subject: Re: [PATCH 0 of 1] Review Request for cpsv: Support preserving and recovering checkpoint replicas during headless state V2 [#1621] Hi Nhat Pham, I stared reviewing this patch , so can please provide README file with scope and limitations , that will help to define testing/reviewing scope . Following are minimum things we can keep in mind while reviewing/accepting patch , - Not effecting existing functionality - during headless state applications may behave like during CPND restart case - The minimum functionally of application works - The behavior of application will be consistent with other saf services like imm/amf behavior during headless state. So please do provide any additional detailed in README if any of the above is deviated , that allow users to know about the limitations/deviation. -AVM On 1/4/2016 3:15 PM, Nhat Pham wrote: Summary: cpsv: Support preserving and recovering checkpoint replicas during headless state [#1621] Review request for Trac Ticket(s): #1621 Peer Reviewer(s): mahesh.va...@oracle.com <mailto:mahesh.va...@oracle.com> ; anders.wid...@ericsson.com <mailto:anders.wid...@ericsson.com> Pull request to: mahesh.va...@oracle.com <mailto:mahesh.va...@oracle.com> Affected branch(es): default Development branch: default -------------------------------- Impacted area Impact y/n -------------------------------- Docs n Build system n RPM/packaging n Configuration files n Startup scripts n SAF services y OpenSAF services n Core libraries n Samples n Tests n Other n Comments (indicate scope for each "y" above): --------------------------------------------- changeset faec4a4445a4c23e8f630857b19aabb43b5af18d Author: Nhat Pham <mailto:nhat.p...@dektech.com.au> <nhat.p...@dektech.com.au> Date: Mon, 04 Jan 2016 16:34:33 +0700 cpsv: Support preserving and recovering checkpoint replicas during headless state [#1621] Background: ---------- This enhancement supports to preserve checkpoint replicas in case both SCs down (headless state) and recover replicas in case one of SCs up again. If both SCs goes down, checkpoint replicas on surviving nodes still remain. When a SC is available again, surviving replicas are automatically registered to the SC checkpoint database. Content in surviving replicas are intacted and synchronized to new replicas. When no SC is available, client API calls changing checkpoint configuration which requires SC communication, are rejected. Client API calls reading and writing existing checkpoint replicas still work. Limitation: The CKPT service does not support recovering checkpoints in following cases: - The checkpoint which is unlinked before headless. - The non-collocated checkpoint has active replica locating on SC. - The non-collocated checkpoint has active replica locating on a PL and this PL restarts during headless state. In this cases, the checkpoint replica is destroyed. The fault code SA_AIS_ERR_BAD_HANDLE is returned when the client accesses the checkpoint in these cases. The client must re-open the checkpoint. While in headless state, accessing checkpoint replicas does not work if the node which hosts the active replica goes down. It will back working when a SC available again. Solution: --------- The solution for this enhancement includes 2 parts: 1. To destroy un-recoverable checkpoint described above when both SCs are down: When both SCs are down, the CPND deletes un-recoverable checkpoint nodes and replicas on PLs. Then it requests CPA to destroy corresponding checkpoint node by using new message CPA_EVT_ND2A_CKPT_DESTROY 2. To update CPD with checkpoint information When an active SC is up after headless, CPND will update CPD with checkpoint information by using new message CPD_EVT_ND2D_CKPT_INFO_UPDATE instead of using CPD_EVT_ND2D_CKPT_CREATE. This is because the CPND will create new ckpt_id for the checkpoint which might be different with the current ckpt id if the CPD_EVT_ND2D_CKPT_CREATE is used. The CPD collects checkpoint information within 6s. During this updating time, following requests is rejected with fault code SA_AIS_ERR_TRY_AGAIN: - CPD_EVT_ND2D_CKPT_CREATE - CPD_EVT_ND2D_CKPT_UNLINK - CPD_EVT_ND2D_ACTIVE_SET - CPD_EVT_ND2D_CKPT_RDSET Complete diffstat: ------------------ osaf/libs/agents/saf/cpa/cpa_proc.c | 52 +++++++++++++++++++++++++++++++++++ osaf/libs/common/cpsv/cpsv_edu.c | 43 +++++++++++++++++++++++++++++ osaf/libs/common/cpsv/include/cpd_cb.h | 3 ++ osaf/libs/common/cpsv/include/cpd_imm.h | 1 + osaf/libs/common/cpsv/include/cpd_proc.h | 7 ++++ osaf/libs/common/cpsv/include/cpd_tmr.h | 3 +- osaf/libs/common/cpsv/include/cpnd_cb.h | 1 + osaf/libs/common/cpsv/include/cpnd_init.h | 2 + osaf/libs/common/cpsv/include/cpsv_evt.h | 20 +++++++++++++ osaf/services/saf/cpsv/cpd/Makefile.am | 3 +- osaf/services/saf/cpsv/cpd/cpd_evt.c | 229 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++ osaf/services/saf/cpsv/cpd/cpd_imm.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ osaf/services/saf/cpsv/cpd/cpd_init.c | 20 ++++++++++++- osaf/services/saf/cpsv/cpd/cpd_proc.c | 309 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ osaf/services/saf/cpsv/cpd/cpd_tmr.c | 7 ++++ osaf/services/saf/cpsv/cpnd/cpnd_db.c | 16 ++++++++++ osaf/services/saf/cpsv/cpnd/cpnd_evt.c | 22 +++++++++++++++ osaf/services/saf/cpsv/cpnd/cpnd_init.c | 23 ++++++++++++++- osaf/services/saf/cpsv/cpnd/cpnd_mds.c | 13 ++++++++ osaf/services/saf/cpsv/cpnd/cpnd_proc.c | 314 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 20 files changed, 1189 insertions(+), 11 deletions(-) Testing Commands: ----------------- - Testing, Expected Results: -------------------------- - Conditions of Submission: ------------------------- <<HOW MANY DAYS BEFORE PUSHING, CONSENSUS ETC>> Arch Built Started Linux distro ------------------------------------------- mips n n mips64 n n x86 n n x86_64 n n powerpc n n powerpc64 n n Reviewer Checklist: ------------------- [Submitters: make sure that your review doesn't trigger any checkmarks!] Your checkin has not passed review because (see checked entries): ___ Your RR template is generally incomplete; it has too many blank entries that need proper data filled in. ___ You have failed to nominate the proper persons for review and push. ___ Your patches do not have proper short+long header ___ You have grammar/spelling in your header that is unacceptable. ___ You have exceeded a sensible line length in your headers/comments/text. ___ You have failed to put in a proper Trac Ticket # into your commits. ___ You have incorrectly put/left internal data in your comments/files (i.e. internal bug tracking tool IDs, product names etc) ___ You have not given any evidence of testing beyond basic build tests. Demonstrate some level of runtime or other sanity testing. ___ You have ^M present in some of your files. These have to be removed. ___ You have needlessly changed whitespace or added whitespace crimes like trailing spaces, or spaces before tabs. ___ You have mixed real technical changes with whitespace and other cosmetic code cleanup changes. These have to be separate commits. ___ You need to refactor your submission into logical chunks; there is too much content into a single commit. ___ You have extraneous garbage in your review (merge commits etc) ___ You have giant attachments which should never have been sent; Instead you should place your content in a public tree to be pulled. ___ You have too many commits attached to an e-mail; resend as threaded commits, or place in a public tree for a pull. ___ You have resent this content multiple times without a clear indication of what has changed between each re-send. ___ You have failed to adequately and individually address all of the comments and change requests that were proposed in the initial review. ___ You have a misconfigured ~/.hgrc file (i.e. username, email etc) ___ Your computer have a badly configured date and time; confusing the the threaded patch review. ___ Your changes affect IPC mechanism, and you don't present any results for in-service upgradability test. ___ Your changes affect user manual and documentation, your patch series do not contain the patch that updates the Doxygen manual. ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. 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