The reverse is true for TPG with this is actually, truly AO for LUN 2 and ANO for LUN 1.
On some active/passive ALUA-capable arrays, you may discover interface teams with a€?Standbya€? AAS in the place of a€?ANOa€? on the non-owner SP.
Asymmetric Access County
Harbors in an ALUA TPG could be in identical AAS all the time with respect to certain LUN. The TPG’s AAS were reported with the initiators in response towards the DOCUMENT TPGS order. The TPG descriptor are reported in byte 1 of this response.
Transitioning-The TPG AAS is within the procedure for switching from a single county to a different. If the SP of an AO TPG is rebooted or perhaps is taken off-line, or if perhaps the SAN (storage area network) admin by hand moves LUN control (on EMC CLARiiON, this can be acknowledged trespass), the AAS of this TPG regarding different SP modifications to AO. While this processes are ongoing, the TPG AAS is actually transitioning.
As the TPG is within this county, obtaining needs from initiators go back ACTIVE or a CHECK STATE with feel important never READY and ASC (additional good sense laws) PRACTICAL UNIT NOT AVAILABLE or ASYMMETRIC ACCESSIBILITY STATE CHANGEOVER.
Standby-This state is comparable to a passive SP in a non-ALUA setting as well as on some ALUA-capable arrays. It returns a CHECK SITUATION with sense essential NOT EAGER.
After TPG is in this AAS, they supports a subset of directions that it takes when it’s in AO AAS:
Unavailable-This AAS is normally seen as soon as the TPG’s access to the LUN is restricted due to hardware problems or any other SCSI device limits. A TPG in this condition is unable to transition to AO or ANO until the mistake subsides.
ESXi 6 sends the I/O to TPGs which happen to be in AO AAS, however, if they are not available, I/O is distributed to TPGs which can be in ANO AAS. When the storage space variety gets continual I/O on TPGs that are in ANO AAS, the collection transitions the TPG’s condition to AO AAS. Which produces that modification depends on the ALUA administration form with the storage space variety (look at then area).
ALUA Control Settings
This is accomplished via some directions and feedback to and from the storage arrays. These commands are listed below:
INQUIRY-According to SPC-3, area 6.4.2, responding for this demand, a selection comes back particular pages regarding the VPD (vital product information) or EVPD (longer essential goods facts). The inquiry data returned as a result for this demand consists of the TPGS industry. In the event the came back benefits where area was nonzero, that device (LUN) aids ALUA. (See Table 6.3, after within this part, for relationship within value of the TPGS area and AAS administration modes.)
SET TARGET SLOT GROUPS (ready TPGs)-This order demands your storing selection put the AAS of most ports in given TPGs. For instance, a TPG’s AAS can transition from ANO to AO through the ready TPGs order.
Desk 6.1 ALUA AAS management settings
Not Supported-The response to the REPORT TPGs and ready TPGs instructions is incorrect. Which means the storage space variety will not support ALUA or, when it comes to EMC CLARiiON, the initiator registers are not designed in a mode that aids ALUA.
Implicit-The array responds to REPORT TPGs yet not put TPGs directions. In such a case, placing the TPG’s AAS is carried out merely by the space array.
Explicit-The variety reacts to both REPORT TPGs and ready TPGs commands. In cases like this, establishing the TPG’s AAS can be done merely because of the initiator.