Optimize the CSI code for rescanning the device about ibm-powervs-block-csi-driver

[Madhan-SWE]

/assign

[Madhan-SWE]

Explored SCSIs, LUNs, Disk Attachment Steps.

Currently we are using two methods to scan the newly attached disks.
Method 1: Rescanning the scsi bus by executing the script /usr/bin/rescan-scsi-bus.sh
Method 2: Rescanning the host scsi adapters one by one ex: echo "- - -" > /sys/class/scsi_host/host0/scan

Both of the above methods are used one after the other on NodeStageVolume Operation.
Rescanning the SCSI bus prints too many logs on the UI and some times hung executing which causes the infinite wait for NodeStageVolume.

Sample output

[root@madhan-1-kube-1-22-2 ~]# /usr/bin/rescan-scsi-bus.sh

Scanning host 0 for  SCSI target IDs  0 1 2 3 4 5 6 7, all LUNs
Scanning host 1 for  all SCSI target IDs, all LUNs
 Scanning for device 1 0 0 0 ...^M Scanning for device 1 0 0 0 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 00
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 1 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 01
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 3 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 03
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 10 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 10
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 11 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 11
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 12 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 12
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 13 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 13
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 14 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 14
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 15 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 15
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 16 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 16
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 17 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 17
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 18 ...
OLD: Host: scsi1 Channel: 00 Id: 00 Lun: 18
      Vendor: IBM      Model: 2145             Rev: 0000
      Type:   Direct-Access                    ANSI SCSI revision: 06
 Scanning for device 1 0 0 19 ...
................
................
................
................
................
................
0 new or changed device(s) found.
0 remapped or resized device(s) found.
0 device(s) removed.

Where as scanning the host adapters is faster and not printing anything on the terminal.
Which also does the same operation of scanning the new device on each host's scsi adapter.

Sample output

[root@madhan-1-kube-1-22-2 ~]# echo "- - -" > /sys/class/scsi_host/host0/scan
[root@madhan-1-kube-1-22-2 ~]# echo "- - -" > /sys/class/scsi_host/host1/scan
[root@madhan-1-kube-1-22-2 ~]# echo "- - -" > /sys/class/scsi_host/host2/scan
[root@madhan-1-kube-1-22-2 ~]# echo "- - -" > /sys/class/scsi_host/host3/scan
[root@madhan-1-kube-1-22-2 ~]# echo "- - -" > /sys/class/scsi_host/host4/scan

Conclusion
RescanSCSIBus can be removed and RescanSCSIHost Adapters can only be used

[Madhan-SWE]

Created a disk and attached to the node from IBM Cloud.
Disk WWN: 60050768108181D628000000000048D8

Getting the disks by id:

[root@madhan-1-kube-1-22-2 powervs-csi-driver]# ls -lF /dev/disk/by-id/
total 0
lrwxrwxrwx. 1 root root 10 Nov 20 00:08 dm-name-mpatha -> ../../dm-0
lrwxrwxrwx. 1 root root 11 Nov 20 00:08 dm-name-mpatha1 -> ../../dm-14
...
...
lrwxrwxrwx. 1 root root 10 Nov 20 00:08 dm-uuid-mpath-360050768108181d62800000000004027 -> ../../dm-0
lrwxrwxrwx. 1 root root 10 Nov 20 00:08 dm-uuid-mpath-360050768108181d628000000000044f3 -> ../../dm-8
...
...
lrwxrwxrwx. 1 root root 10 Nov 24 06:54 scsi-360050768108181d62800000000004027 -> ../../dm-0
lrwxrwxrwx. 1 root root 11 Nov 20 00:08 scsi-360050768108181d62800000000004027-part1 -> ../../dm-14
...
...
lrwxrwxrwx. 1 root root 11 Nov 20 00:08 wwn-0x60050768108181d62800000000004027-part1 -> ../../dm-14
lrwxrwxrwx. 1 root root 11 Nov 20 00:08 wwn-0x60050768108181d62800000000004027-part2 -> ../../dm-15

Disk with expected WWN not found.
Scanning the host adapter

[root@madhan-1-kube-1-22-2 ~]# echo "- - -" > /sys/class/scsi_host/host0/scan
[root@madhan-1-kube-1-22-2 ~]# echo "- - -" > /sys/class/scsi_host/host1/scan
[root@madhan-1-kube-1-22-2 ~]# echo "- - -" > /sys/class/scsi_host/host2/scan
[root@madhan-1-kube-1-22-2 ~]# echo "- - -" > /sys/class/scsi_host/host3/scan
[root@madhan-1-kube-1-22-2 ~]# echo "- - -" > /sys/class/scsi_host/host4/scan

Expected disk WWN found:

[root@madhan-1-kube-1-22-2 powervs-csi-driver]# ls -lF /dev/disk/by-id/
total 0
...
...
...
lrwxrwxrwx. 1 root root 11 Nov 24 06:54 wwn-0x60050768108181d628000000000048d8 -> ../../dm-41
...
...
...