3PAR Users Group

Rest ALUA on a host
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Author:  rbird97 [ Thu Dec 06, 2018 10:21 am ]
Post subject:  Rest ALUA on a host


We are having difficulties on the network side of our FCOE infrastructure and that has resulting in us losing half our paths to the storage array. After fixing it some of the hosts have come back with full pathing while some have not.

I was told that this may be due to ALUA not recognizing dead paths and that if you reset the ALUA it should work on it.

What I don't know is how to reset ALUA. any ideas?

Author:  ailean [ Thu Dec 06, 2018 12:47 pm ]
Post subject:  Re: Rest ALUA on a host

I've seen this on some Solaris hosts before after fabric issues, I believe they just had to manually rescan the HBAs to look for current paths. No idea of the commands alas, our VMware hosts seem to recover but Solaris won't normally trust a dead path once marked until someone manually tells it.

Only other hosts we have are a couple of Windows ones, think they recovered on there own too so might be an UNIX thing.

Author:  markinnz [ Thu Dec 06, 2018 4:13 pm ]
Post subject:  Re: Rest ALUA on a host

ALUA is not something you reset, it's an array side feature, sounds to me you might have configured the wrong persona type on the array for the hosts or the hosts have not been correctly configured for multipathing.

If you look at the persona types :

showhost -listpersona
Persona_Id Persona_Name Persona_Caps
1 Generic UARepLun,SESLun
2 Generic-ALUA UARepLun,SESLun,ALUA
6 Generic-legacy --
7 HPUX-legacy VolSetAddr,Lun0SCC
8 AIX-legacy NACA
10 ONTAP-legacy SoftInq
11 VMware SubLun,ALUA
13 HPUX UARepLun,VolSetAddr,SESLun,ALUA,Lun0SCC
15 WindowsServer UARepLun,SESLun,ALUA,WSC

ALUA allows the array to send notificationsa to the host that there have been things like path changes to VLUNs and also which paths are the best to use when accessing a vlun.
UARepLun lets the array notify the host that there are VLUN changes (vluns added or removed)
SESLun adds a VLUN 254 to allow host explorer to register hosts with the array
SubLun addes VLUN 256 which allows VMware to send commands to the array .. used for VVols etc
VolSetAddr lets HPUX hosts work .. cause HPUX is a PITA for storage :-)
and the others I can't remember.

You need to make sure you follow the host connectivity guides for connecting your server+OS to the 3PAR to the leter. Older versions of OSs may need different persona settings to newer, get it wrong and things go weird.

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