White Paper- Windows Server High Availability with Microsoft MPIO

Appendix E - MPIO timers

1. PathVerifyEnabled:

This flag enables path verification by MPIO on all paths every N seconds (where N depends on the value set in PathVerificationPeriod).

Type is boolean and must be filled with either 0 (disbale) or 1 (enable). By default, it is disabled.

2. PathVerificationPeriod: This setting is used to indicate the periodicity (in seconds) with which

MPIO has been requested to perform path verification. This field is only honored if PathVerifyEnabled is TRUE.

This timer is specified in seconds. The default is 30 seconds. The max allowed is MAXULONG. 3. PDORemovePeriod:

This setting controls the amount of time (in seconds) that the

multipath pseudo-LUN will continue to remain in system memory, even after losing all paths to the device.

This timer is specified in seconds. The default is 20 seconds. The max allowed is MAXULONG.

This setting specifies the number of times a failed IO if the DSM

determines that a failing request must be retried. This is invoked when DsmInterpretError() returns Retry = TRUE. The default setting is 3.

This setting specifies the interval of time (in seconds) after which a failed request is retried (after the DSM has decided so, and assuming that the IO has been retried lesser number of times than RetryCount).

This value is specified in seconds. The default is 1 second

4. RetryCount:

5. RetryInterval:

Highly Available Storage: Multipath Solutions in Windows Server 2008 and Windows Server 2003

47

Appendix F – Acronyms:

ALUA DDK DSM FC FS FT GUI HBA I/O IHV IIS iSCSI ISV IT LUN MPIO MSCS MSDSM NAS NIC NLB OC NTFS PDO PnP RAID SAN SAS SCSI SPC-3 USB WMI WSFC

Asymmetric Logical Unit Access Driver Development Kit Device Specific Module Fibre Channel File System Fault Tolerant

Graphical User Interface Host Bus Adapters Input / Output

Independent Hardware Vendor Internet Information Server Internet SCSI

Independent Software Vendor Information Technology Logical Unit Number Multi-path I/O Microsoft Cluster Microsoft DSM

Network Attached Storage Network Interface Card Network Load Balancing Optional Component New Technology File System Physical Device Object Plug and Play

Redundant Array of Independent Disks Storage Area Network Serial Attached SCSI

Small Computer System Interface SCSI Primary Commands – 3 Universal Serial Bus

Windows Management Interface Windows Failover Clustering

Highly Available Storage: Multipath Solutions in Windows Server 2008 and Windows Server 2003

48