SC Storage Customer Notification: Applying host best practice settings via Dell Storage Manager Client

This alert pertains to Dell Storage Manager Client and host server settings. It contains specific information related to system features and/or functionality.

Alert:

To ensure connectivity during failover and provide optimal IO processing, certain host server settings may need to be adjusted.  The Dell Storage Manager Client has the ability to automatically adjust these settings to ensure the host is in line with Best Practices for Storage Center.  It is highly recommended that the Dell Storage Manager Client is installed on each Linux or Windows host and then use the wizard to configure the host to apply Best Practice settings.  VMware hosts can be configured remotely from the Dell Storage Manager Client running on a Windows or Linux host.  After the settings are applied, the Dell Storage Manager Client may be uninstalled if desired.

The host setup wizards can be launched by right-clicking "Servers" from the Storage tab within Dell Storage Manager Client and choosing Create Server from localhost or Create Server from VMware vSphere or vCenter (see Figure 1) or from the welcome screen when Dell Storage Manager Client is launched (see Figure 2).

Figure 1.



Figure 2.

Best Practices that are applied include the following:

Windows:     

Best Practice: MPIO PDORemovePeriod

Description:  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. 

Best Practice: MPIO PathVerifyEnabled

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

Best Practice: MPIO PathVerificationPeriod

Description:  This setting is used to indicate the periodicity (in seconds) with which MPIO has been requested to perform path verification. 

Best Practice: MPIO RetryCount

Description:  This setting specifies the number of times a failed IO if the DSM determines that a failing request must be retried. 

Best Practice: MPIO RetryInterval

Description:  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 a fewer number of times than RetryCount). 

Best Practice: MPIO PathRecoveryInterval

Description:  Represents the period after which PathRecovery is attempted. This setting is only used if it is not set to 0 and UseCustomPathRecoveryInterval is set to 1. 

Best Practice: MPIO UseCustomPathRecoveryInterval

Description:  If this key exists and is set to 1, it allows the use of PathRecoveryInterval. 

Best Practice: DiskTimeOutValue

Description:  This setting controls how long Windows waits for an IO request before aborting. 

Best Practice: MaxRequestHoldTime

Description:  Maximum time (in seconds) for which requests will be queued if connection to the target is lost and the connection is being retried. 

Best Practice: EnableNOPOut

Description:  If set to non-zero value, the initiator will send NOP OUT PDUs to target if there is no activity for 2 minutes. 

Best Practice: LinkDownTime

Description:  This value determines how long requests will be held in the device queue and retried if the connection to the target is lost. If MPIO is installed this value is used. If MPIO is not installed MaxRequestHoldTime is used instead. 

Best Practice: DiskPathCheckEnabled

Description:  If the DiskPathCheckEnabled key is set to a nonzero value, the MPIO component creates a path recovery worker. 

Best Practice: DiskPathCheckDisabled

Description:  If the DiskPathCheckDisabled key is set to zero, the MPIO component creates a path recovery worker. 

Best Practice: DiskPathCheckInterval

Description:  If the DiskPathCheckInterval key is set to 0, or if the key does not exist, the MPIO component uses a default time interval. 

Linux:

Best Practice: node.conn.timeo.noop_out_interval

Description:  iSCSI layer will send a NOP-Out request to each target every interval value seconds. 

Best Practice: node.conn.timeo.noop_out_timeout

Description:  This sets the iSCSI layer to timeout a NOP-Out request after timeout value seconds.

ESX:

Best Practice: Storage_IO_Control

Description:  SIOC is a means of ensuring that the excessing storage I/O demands of a particular VMDK does not negatively impact the storage I/O of other VMDKs on the same datastore.  SIOC is changed to disabled as Storage Center implements congestion management methods.

Best Practice: Delay ACK

Description: This setting specifies to disable Delay ACK for TCP

Best Practice: StorageDRS

Description: Storage DRS load balances VMs within a datastore cluster based on capacity and/or performance.  This setting is changed to disabled for performance portion and remains enabled for capacity to best integrate with Storage Center.

Best Practice: iSCSI Login Timeout

Description: Large number of iSCSI can occur after network failure, switch reboot or controller failover.  Increasing Login Timeout to better manage Login attempts.

For a step by step illustration of setting up a host server using the automated wizard, see article How to apply host server Best Practice settings using the Dell Storage Manager client.

Resolution:

The host setup wizard is available in:

Enterprise Manager 2015 R1 and greater

Dell Storage Manager 2016 R1 and greater