It is possible to use the SAP HANA Storage API connect in conjunction with an ActiveCluster implementation with preferred paths set for each host. In the event of a single site failure, the Storage APi connector will detach the volumes from compute 1, attach them to compute 2, and then start the instance.
This approach is best considered for Scale Up implementations where the topology is a single worker and single standby node.
1. Install the SAP HANA system, but during installation ensure that an additional system is added with the standby role. The volumes should already be in a POD, stretched to the additional array, and connected to the host group containing both compute instances on both arrays. Each host should also have a preferred path set (if required), this needs to be the same preferred array per host on each array.
In the event of storage failure
The failover will be transparent. Both nodes (worker and standby) will have access to the storage.
Storage failure will show paths failing in one priority group, in this instance the preferred array has remained available.
3624a9370884890ea83bd488200012863 dm-0 PURE,FlashArray
size=512G features='0' hwhandler='1 alua' wp=rw
|-+- policy='queue-length 0' prio=50 status=active
| |- 0:0:2:253 sdi 8:128 active ready running
| |- 0:0:6:253 sdq 65:0 active ready running
| |- 0:0:3:253 sdk 8:160 active ready running
| |- 0:0:5:253 sdo 8:224 active ready running
| |- 1:0:3:253 sdw 65:96 active ready running
| |- 1:0:2:253 sdu 65:64 active ready running
| |- 1:0:7:253 sdae 65:224 active ready running
| `- 1:0:8:253 sdag 66:0 active ready running
`-+- policy='queue-length 0' prio=0 status=enabled
|- 0:0:1:253 sdg 8:96 failed faulty running
|- 0:0:0:253 sde 8:64 failed faulty running
|- 0:0:4:253 sdm 8:192 failed faulty running
|- 0:0:7:253 sds 65:32 failed faulty running
|- 1:0:4:253 sdy 65:128 failed faulty running
|- 1:0:5:253 sdaa 65:160 failed faulty running
|- 1:0:6:253 sdac 65:192 failed faulty running
`- 1:0:9:253 sdai 66:32 failed faulty running
3624a9370884890ea83bd488200012862 dm-1 PURE,FlashArray
size=1.0T features='0' hwhandler='1 alua' wp=rw
|-+- policy='queue-length 0' prio=50 status=active
| |- 0:0:2:254 sdj 8:144 active ready running
| |- 0:0:5:254 sdp 8:240 active ready running
| |- 0:0:3:254 sdl 8:176 active ready running
| |- 0:0:6:254 sdr 65:16 active ready running
| |- 1:0:7:254 sdaf 65:240 active ready running
| |- 1:0:3:254 sdx 65:112 active ready running
| |- 1:0:2:254 sdv 65:80 active ready running
| `- 1:0:8:254 sdah 66:16 active ready running
`-+- policy='queue-length 0' prio=0 status=enabled
|- 0:0:4:254 sdn 8:208 failed faulty running
|- 0:0:1:254 sdh 8:112 failed faulty running
|- 0:0:0:254 sdf 8:80 failed faulty running
|- 0:0:7:254 sdt 65:48 failed faulty running
|- 1:0:4:254 sdz 65:144 failed faulty running
|- 1:0:6:254 sdad 65:208 failed faulty running
|- 1:0:5:254 sdab 65:176 failed faulty running
`- 1:0:9:254 sdaj 66:48 failed faulty running
In the event of host failure
The SAP HANA storage API connector will disconnect the volumes from the failed host and connect them to the standby, starting the instance. Any applications communicating with the instance will need to be aware that the instance has failed over.
Using the GetProcessList function of the sapcontrol utility, it can be seen that the indexserver and hdbxseengine have failover over and are now starting on the standby node.
13.07.2020 05:17:39
GetProcessList
OK
name, description, dispstatus, textstatus, starttime, elapsedtime, pid
hdbdaemon, HDB Daemon, YELLOW, Initializing, 2020 07 13 05:01:49, 0:15:50, 6803
hdbcompileserver, HDB Compileserver, GREEN, Running, 2020 07 13 05:01:53, 0:15:46, 6863
hdbnameserver, HDB Nameserver, GREEN, Running, 2020 07 13 05:01:49, 0:15:50, 6821
hdbpreprocessor, HDB Preprocessor, GREEN, Running, 2020 07 13 05:01:53, 0:15:46, 6866
hdbwebdispatcher, HDB Web Dispatcher, GREEN, Running, 2020 07 13 05:01:54, 0:15:45, 6916
hdbindexserver, HDB Indexserver-SH1, YELLOW, Initializing, 2020 07 13 05:17:32, 0:00:07, 17024
hdbxsengine, HDB XSEngine-SH1, YELLOW, Initializing, 2020 07 13 05:17:32, 0:00:07, 17027