Brand new dynamic character away from multipathing and you will failover necessitates the independency regarding handling and you may controlling an ALUA TPG’s AAS
The opposite holds true for TPG thereupon was, it’s AO for LUN dos and you can ANO to own LUN 1.
On particular energetic/inactive ALUA-capable arrays, you may also get a hold of vent teams that have “Standby” AAS as opposed to “ANO” for the low-owner SP.
Asymmetric Access 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 fresh TPG AAS is within the procedure for altering from a single condition to some other. Particularly, when your SP regarding an enthusiastic AO TPG will be rebooted or is actually taken traditional, or if the fresh new SAN (storage space circle) administrator manually transmits LUN ownership (into the EMC CLARiiON, this might be known as trespass), this new AAS of the TPG to the choice SP transform to help you AO. Although this techniques is actually lingering, the latest TPG AAS is actually transitioning.
While the TPG is in this state, receiving requests from the initiators return Hectic or a Check Updates with sense key Perhaps not In a position and ASC (additional sense code) Analytical Unit Maybe not Accessible or ASYMMETRIC Supply Condition Change.
Standby-This state is similar to a passive SP in a non-ALUA configuration and on certain ALUA-capable arrays. It returns a Examine Status with sense key Maybe not Ready.
If TPG is during it AAS, they helps a great subset out-of sales it accepts whether or not it is in AO AAS:
Unavailable-So it AAS is sometimes seen when the TPG’s entry to the new LUN is restricted down to hardware errors and other SCSI product constraints. A great TPG inside county is unable to change so you’re able to AO otherwise ANO before the mistake subsides.
ESXi six directs the We/O so you’re able to TPGs which can be into the AO AAS, however if they are not available, I/O is sent to help you TPGs that are inside the ANO AAS. Whether your storage selection obtains suffered We/O toward TPGs that will be in the ANO AAS, the fresh range transitions the latest TPG’s state so you can AO AAS. Exactly who tends to make you to definitely transform utilizes this new ALUA management form out-of the newest sites assortment (see the next area).
ALUA Management Modes
This is accomplished through a collection of sales and you may answers so you’re able to and about stores arrays. These types of purchases are listed below:
Query-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.)
Set Target Port Organizations (Set 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 Lay TPGs command.
Dining table six.step one ALUA AAS management modes
Not Supported-The response to the Statement TPGs and Put TPGs commands is invalid. This means that the storage array does not support ALUA or, be2 oturum açın in the case of EMC CLARiiON, the initiator records are not configured in a mode that supports ALUA.
Implicit-The array responds to Report TPGs but not Put TPGs commands. In this case, setting the TPG’s AAS is done only by the storage array.
Explicit-The array responds to both Declaration TPGs and Set TPGs commands. In this case, setting the TPG’s AAS can be done only by the initiator.