I/O Errors due to keepalive timeouts with NVMf RDMA

[jthumshirn@suse.de (Johannes Thumshirn)]

On Mon, Jul 10, 2017@11:46:47AM +0300, Max Gurtovoy wrote:
> >>- What kato is required to not stumble on this?

Tried up to 120 now, still broken.

> >Well, this sounds identically to the path_checker problem we're having
> >in multipathing (and hch complained about several times).
> >There's a rather easy solution to it: don't send keepalives if I/O is
> >running, but rather tack it on the most current I/O packet.
> >In the end, you only want to know if the link is alive; you don't have
> >to transfer any data as such.
> >So if you just add a flag (maybe on the RDMA layer) to the next command
> >to be sent you could easily simulate keepalive without having to send
> >additional commands.
> 
> Hannes,
> This is a good solution and actually the way we work in iSCSI/iSER with
> nopin/nopout.
> Don't you think it should be a ctrl attribute ?

Let me see if I can come up with something.

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Johannes Thumshirn                                          Storage
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