PowerFlex/ScaleIO SDC client connection improvements

[sureshanaparti]

Description

This PR improves the PowerFlex/ScaleIO SDC client connections, includes the following changes.

• Added ScaleIOSDCManager to manage SDC connections, checks clients limit, prepare and unprepare SDC on the hosts.
• Added commands for prepare and unprepare storage clients to prepare/start and stop SDC service respectively on the hosts.
• Introduced config 'storage.pool.connected.clients.limit' at storage level for client limits, currently supported for Powerflex only.
• Added custom stats support for storage pool, through listStoragePools API (when storagecustomstats=true). For Powerflex, it returns latest ConnectedSDCCount.

Types of changes

• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] Enhancement (improves an existing feature and functionality)
• [ ] Cleanup (Code refactoring and cleanup, that may add test cases)
• [ ] build/CI

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• [x] Major
• [ ] Minor

Bug Severity

• [ ] BLOCKER
• [ ] Critical
• [ ] Major
• [ ] Minor
• [ ] Trivial

Screenshots (if appropriate):

How Has This Been Tested?

How did you try to break this feature and the system with this change?

[rohityadavcloud]

@blueorangutan test alma8 kvm-alma8

[blueorangutan]

@rohityadavcloud a [SL] Trillian-Jenkins test job (alma8 mgmt + kvm-alma8) has been kicked to run smoke tests

[blueorangutan]

[SF] Trillian test result (tid-10677) Environment: kvm-centos7 (x2), Advanced Networking with Mgmt server 7 Total time taken: 47223 seconds Marvin logs: https://github.com/blueorangutan/acs-prs/releases/download/trillian/pr9268-t10677-kvm-centos7.zip Smoke tests completed. 131 look OK, 0 have errors, 0 did not run Only failed and skipped tests results shown below:

Test	Result	Time (s)	Test File

[sureshanaparti]

Merging based on review, manual & smoke tests.

[blueorangutan]

[SF] Trillian test result (tid-10683) Environment: kvm-alma8 (x2), Advanced Networking with Mgmt server a8 Total time taken: 43532 seconds Marvin logs: https://github.com/blueorangutan/acs-prs/releases/download/trillian/pr9268-t10683-kvm-alma8.zip Smoke tests completed. 130 look OK, 1 have errors, 0 did not run Only failed and skipped tests results shown below:

Test	Result	Time (s)	Test File
test_07_arping_in_vr	Failure	5.21	test_diagnostics.py