New dynamic character off multipathing and you may failover requires the independence away from managing and you can dealing with an ALUA TPG’s AAS

The opposite is true for TPG thereupon are, it’s AO to possess LUN dos and you can ANO having LUN 1.

For the certain effective/inactive ALUA-able to arrays, you can even find port communities having “Standby” AAS as opposed to “ANO” for the non-proprietor SP.

Asymmetric Accessibility County

Ports in an ALUA TPG can be in the same AAS at all times with respect to a given LUN. The TPG’s AAS are reported to the initiators in response to the Declaration TPGS command. The TPG descriptor is reported in byte 1 of that response.

Transitioning-The TPG AAS is in the procedure for altering from one condition to some other. Particularly, adult sex chat should your SP off an AO TPG is rebooted or try removed off-line, or if perhaps the new SAN (space for storage circle) admin by hand transfers LUN possession (on the EMC CLARiiON, this really is called trespass), this new AAS of the TPG towards the alternative SP change to help you AO. Although this procedure was ongoing, the fresh TPG AAS is transitioning.

While the TPG is in this state, receiving requests from the initiators return Active or a Glance at Standing with sense key Maybe not In a position and ASC (additional sense code) Analytical Product Perhaps not Obtainable or ASYMMETRIC Access County Transition.

Standby-This state is similar to a passive SP in a non-ALUA configuration and on certain ALUA-capable arrays. It returns a Take a look at Status with sense key Not Able.

When the TPG is within that it AAS, it aids an excellent subset out of orders so it allows whether or not it is within AO AAS:

Unavailable-So it AAS is usually viewed in the event that TPG’s the means to access brand new LUN is bound down seriously to gear mistakes or other SCSI equipment limitations. An effective TPG inside condition cannot changeover in order to AO or ANO before mistake subsides.

ESXi six directs the fresh new I/O to TPGs that are when you look at the AO AAS, however, if they’re not available, I/O is sent to help you TPGs which might be within the ANO AAS. In case your storage number gets sustained I/O toward TPGs which might be inside the ANO AAS, new selection transitions this new TPG’s condition to AO AAS. Which helps make one change hinges on the newest ALUA management setting off the latest shop range (comprehend the second section).

ALUA Government Methods

This is accomplished through a set of orders and you can answers so you’re able to and you will throughout the storage arrays. Such requests are as follows:

Inquiry-According to SPC-3, section 6.4.2, in response to this command, an array returns certain pages of the VPD (vital product data) or EVPD (extended vital product data). The inquiry data returned in response to this command includes the TPGS field. If the returned value in that field is nonzero, that device (LUN) supports ALUA. (See Table 6.3, later in this chapter, for the correlation between the value of the TPGS field and AAS management modes.)

Place Address Port Teams (Lay TPGs)-This command requests that the storage array set the AAS of all ports in specified TPGs. For example, a TPG’s AAS can transition from ANO to AO via the Place TPGs command.

Desk 6.1 ALUA AAS management modes

Not Supported-The response to the Report TPGs and Set TPGs commands is invalid. This means that the storage array does not support ALUA or, in the case of EMC CLARiiON, the initiator records are not configured in a mode that supports ALUA.

Implicit-The array responds to Declaration TPGs but not Set TPGs commands. In this case, setting the TPG’s AAS is done only by the storage array.

Explicit-The array responds to both Statement TPGs and Lay TPGs commands. In this case, setting the TPG’s AAS can be done only by the initiator.