Dell UCPM-800 Multipath Support

Multipath Support

Multipathing solutions use redundant physical path components such as adapters, cables, and switches

to create logical paths between the server and the storage device. In the event that one or more of these

components fails, multipathing logic uses an alternate path for I/O so that applications can still access

their data.

In the Fault Tolerant Shared PERC 8 card configuration, the PowerEdge VRTX system has two Shared

PERC 8 cards in an active-passive mode. In this configuration, each host server can access the same

virtual disk through both cards. In the absence of a multipath driver, the operating system identifies the

single disk as two identical disks. The multipath driver aggregates the two disks into a single disk with

redundant access that is then presented to the operating system. The MPIO driver determines the path

chosen for any I/O sent to the virtual disk. Any I/O directed to the passive card is internally redirected to

the active card for completion.

Configuring Multipath Support In Windows

In Windows, multipath support is enabled by installing the MPIO driver. The Shared PERC 8 device must

be added to the list of devices that are aggregated by MPIO after the device driver is installed. Perform the

following steps to add the Shared PERC 8 card:

1. Open the MPIO control panel.

2. Click the Discover Multi-Paths tab.

3. Select DELL Shared PERC8 and click Add.

This is only a one time setup procedure. After the Shared PERC 8 device is added to the list of devices,

the MPIO driver aggregates all instances of the same virtual disk into a single one. The recommended

multipath policy for Windows is round-robin (with subset).

Configuring Multipath Support In VMWare

In VMWare, multipath support is automatically enabled using Native Multipathing (NMP) for all Shared

PERC 8 cards in Dell versions of the ESXi operating systems.

NOTE: The recommended multipath policy is Most Recently Used (MRU).

Multipath support in Linux

Currently, Linux support is not offered by Dell on fault tolerant VRTX configurations.

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Contents

Main Notes, Cautions, and Warnings Contents 3 Deploying The Shared PERC 8 Card................................................................22 Page About The Shared PERC 8 Card Configurations of the Shared PERC 8 card Specifications of a Shared PERC 8 card Page Supported Operating Systems Best Practices For Shared PERC 8 Related Documentation Locating your system Service Tag Contacting Dell Documentation Feedback Shared PERC 8 Card Features Physical Disk Power Management Consistency Checks Virtual Disk Initialization Background Initialization Of Virtual Disks Physical Disk Roaming Using Physical Disk Roaming FastPath Virtual Disk Migration Migrating Virtual Disks If The Target System Is Turned Off Migrating Virtual Disks If The Target System Is Turned On Virtual Disk Cache Policies Virtual Disk Write Cache Policies Write-Back Conditions Under Which Write-Back Is Employed Conditions Under Which Forced Write-Back With No Battery Is Employed Write-through Physical Disk Write Cache Policy Fault Tolerance The SMART Feature Patrol Read Physical disk failure detection Physical Disk Hot Swapping Auto Replacement Of A Virtual Disk Member And Revertible Hot Spares Shared PERC 8 Card Cache Preservation Cache Preservation With Non-Volatile Cache Battery Transparent Learn Cycle TLC Time Frame Conditions For Replacing The Battery The Controller Failover Feature Multipath Support Configuring Multipath Support In Windows Configuring Multipath Support In VMWare Multipath support in Linux Deploying The Shared PERC 8 Card Installing A New Shared PERC 8 Card Replacing A Shared PERC 8 Card Prerequisites For Removing The Shared PERC 8 Card Removing The Shared PERC 8 Card Page Installing The Shared PERC 8 Card Post-Installation Tasks For Shared PERC 8 Card Firmware installation or update Updating firmware Driver Installation Downloading Drivers From The Dell Systems Service And Diagnostic Tools Media For Windows Installing Or Updating Windows Drivers For Shared PERC 8 Installing Or Updating Linux Drivers For Shared PERC 8 Installing Or Updating The Driver Package On RHEL Using KMOD Support Installing Or Updating The Driver Package On SLES Using KMP Support Installing Or Updating VMware Drivers For Shared PERC 8 Management Applications For Shared PERC 8 Card Troubleshooting Performance variations between write-back and write- through cache modes Shared PERC 8 Card Boots Into Safe Mode Degraded State Of Virtual Disks General Issues Shared PERC 8 Card Has Yellow Exclamation Mark In Device Manager Shared PERC 8 Card Not Seen In Device Manager Critical Errors Or Disk Warning Messages Seen In The Windows Event Log Physical disk issues Incorrect Number of Virtual Disks Displayed In Windows Disk Manager Physical Disk In Failed State Unable to rebuild a fault tolerant virtual disk Fatal Error Or Data Corruption Reported Physical Disk Displayed As Blocked By Management Application Multiple Disks Become Inaccessible Rebuilding A Failed Physical Disk Virtual Disk Fails During Rebuild Using A Global Hot Spare Virtual Disk Fails During Rebuild Using A Dedicated Hot Spare Physical disk takes a long time to rebuild Controller cache issues SMART Errors SMART Error Detected On A Physical Disk In A Redundant Virtual Disk SMART Error Detected On A Physical Disk In A Non-Redundant Virtual Disk Auto Replacement Member Errors Source Disk Fails Target Disk Fails General Disk Fails Hard-Drive Indicator Patterns Getting help Contacting Dell Locating your system Service Tag Documentation feedback