Date: Thu, 18 Mar 2021 13:54:53 +0100 From: Michael Tuexen <michael.tuexen@lurchi.franken.de> To: "Scheffenegger, Richard" <Richard.Scheffenegger@netapp.com> Cc: Rick Macklem <rmacklem@uoguelph.ca>, Jason Breitman <jbreitman@tildenparkcapital.com>, "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: NFS Mount Hangs Message-ID: <2890D243-AF46-43A4-A1AD-CB0C3481511D@lurchi.franken.de> In-Reply-To: <SN4PR0601MB3728780CE9ADAB144B3B681486699@SN4PR0601MB3728.namprd06.prod.outlook.com> References: <C643BB9C-6B61-4DAC-8CF9-CE04EA7292D0@tildenparkcapital.com> <3750001D-3F1C-4D9A-A9D9-98BCA6CA65A4@tildenparkcapital.com> <33693DE3-7FF8-4FAB-9A75-75576B88A566@tildenparkcapital.com> <YQXPR0101MB0968DC18E00833DE2969C636DD6A9@YQXPR0101MB0968.CANPRD01.PROD.OUTLOOK.COM> <SN4PR0601MB3728780CE9ADAB144B3B681486699@SN4PR0601MB3728.namprd06.prod.outlook.com>
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> On 18. Mar 2021, at 13:42, Scheffenegger, Richard =
<Richard.Scheffenegger@netapp.com> wrote:
>=20
>>> Output from the NFS Client when the issue occurs # netstat -an | =
grep=20
>>> NFS.Server.IP.X
>>> tcp 0 0 NFS.Client.IP.X:46896 NFS.Server.IP.X:2049 =
FIN_WAIT2
>> I'm no TCP guy. Hopefully others might know why the client would be =
stuck in FIN_WAIT2 (I vaguely recall this means it is waiting for a =
fin/ack, but could be wrong?)
>=20
> When the client is in Fin-Wait2 this is the state you end up when the =
Client side actively close() the tcp session, and then the server also =
ACKed the FIN.=20
Jason noted:
When the issue occurs, this is what I see on the NFS Server.
tcp4 0 0 NFS.Server.IP.X.2049 NFS.Client.IP.X.51550 =
CLOSE_WAIT =20
which corresponds to the state on the client side. The server received =
the FIN
from the client and acked it. The server is waiting for a close call to =
happen.
So the question is: Is the server also closing the connection?
Best regards
Michael
> This will last for ~2 min or so, but is asynchronous. However, the =
same 4-tuple can not be reused during this time.
>=20
> With other words, from the socket / TCP, a properly executed active =
close() will end up in this state. (If the other side initiated the =
close, a passive close, will not end in this state)
>=20
>=20
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