Sun Storage Flexline 380 Array
 
Sun Storage 6580 Array
 
Sun Storage 2540-M2 Array
 
Sun Storage 6130 Array
 
Sun Storage 2540 Array
 
Sun Storage 2510 Array
 
Sun Storage 6540 Array
 
Sun Storage 6180 Array
 
Sun Storage 6780 Array
 
Sun Storage 2530 Array
 
Sun Storage 2530-M2 Array
 
Sun Storage 6140 Array
 

PLA-Support>Sun Systems>DISK>Arrays>SN-DK: FLX300_65xx_6780
 

In this Document

Purpose

Details

Applies to:

Purpose

This document provides information about automatic volume transfer (AVT) related to Sun Storage 2500, 2500-M2 and 6000 arrays.

Details

Automatic Volume Transfer (AVT) is an event type that you will see in the major event log (MEL) of the disk array.  Typical postings in the MEL are "Automatic volume transfer started" (Event number 400E) and "Automatic volume transfer completed" (Event number 202F).

A regular AVT event occurs when an I/O is issued to a controller for a LUN that the controller does not own. LUN ownership is automatically transferred to the non-owning controller and that controller honors the I/O request. A forced AVT occurs when a regular AVT fails to complete for some reason.  The usual reason for this failure is quiescence cannot be achieved on the LUN on the owning controller within the quiescent timeout period. A regular AVT event usually occurs on a LUN for one of two reasons:

• A host is having communication problems with a LUN, normally because of a host side I/O path issue.
• The preferred path to a LUN is not configured correctly on a host.

 If a regular AVT fails to complete, the controller attempting to honor the I/O request that caused the AVT issues a forced AVT on the LUN.
 When a forced AVT is issued, the issuing controller (the one which does not own the LUN) performs the following steps:

1. Sets the other controller Passive/offline.
2. Takes LUN ownership and all cached data for that LUN.
3. Holds the other controller in reset.
4. Releases the other controller from reset.
5. Sets the other controller Active/online, but does not change LUN ownership back to the original controller.

A forced AVT can also occur in classic RDAC mode for the same reasons it occurs in AVT mode, i.e., quiescence can't be achieved on a LUN within the timeout period.  The only difference between the two failover methods as far as a forced AVT is concerned is the way in which the original LUN transfer is requested.

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