CentOS - Sep 2017 - mounting an nfs4 file system as v4.0 in CentOS 7.4?

CentOS 7.4 client mounting a CentOS 7.4 server filesystem over nfs4.

nfs seems to be much slower since the upgrade to 7.4, so I thought it
might be nice to mount the directory as v4.0 rather than the new default
of v4.1 to see if it makes a difference.

The release notes state, without an example:

"You can retain the original behavior by specifying 0 as the minor
version"

nfs(5) states:

**
Recent kernels allow the minor version to be specified using the
vers= option.  For example, specifying vers=4.1 is the same 
as specifying vers=4,minorversion=1.
**

but in fstab or on the command line, using either form (vers=4.0
or vers=4,minorversion=0), if I run mount afterwards, I still see
vers=4.1 for the mount.

I'm missing something obvious, but the only thing obvious to me
is that I can't see it.

Any help is greatly appreciated.

Cheers,
Zube

Is anyone running any Areca RAID controllers with the latest CentOS 7 kernel,
3.10.0-693.2.2.el7.x86_64?  We recently updated (from
3.10.0-514.26.2.el7.x86_64), and we?ve started having lots of problems.  To add
to the confusion, there?s also a hardware problem (either with the controller or
the backplane most likely) that we?re in the process of analyzing.  Regardless,
we have an ARC1883i, and with the older kernel the system is stable, but with
the new kernel it locks up within 1-12 hours of boot, with errors in
/var/log/messages that start with things like
kernel: arcmsr0: abort device command of scsi id = 0 lun = 0
(that is indeed the RAID scsi device) and within a few minutes of those also
things like
Oct 19 23:06:57 radon kernel: INFO: task xfsaild/dm-9:913 blocked for more than
120 seconds.
Oct 19 23:06:57 radon kernel: "echo 0 >
/proc/sys/kernel/hung_task_timeout_secs" disables this message.
Oct 19 23:06:57 radon kernel: xfsaild/dm-9    D ffff88103eaa2000     0   913    
2 0x00000080
Oct 19 23:06:57 radon kernel: ffff881033f67d48 0000000000000046 ffff88102f7c4f10
ffff881033f67fd8
Oct 19 23:06:57 radon kernel: ffff881033f67fd8 ffff881033f67fd8 ffff88102f7c4f10
ffff88103ada5300
Oct 19 23:06:57 radon kernel: 0000000000000000 ffff88102f7c4f10 ffff88103afe4528
ffff88103eaa2000
Oct 19 23:06:57 radon kernel: Call Trace:
Oct 19 23:06:57 radon kernel: [<ffffffff816a94e9>] schedule+0x29/0x70
Oct 19 23:06:57 radon kernel: [<ffffffffc04d1d16>]
_xfs_log_force+0x1c6/0x2c0 [xfs]
Oct 19 23:06:57 radon kernel: [<ffffffff810c4810>] ?
wake_up_state+0x20/0x20
Oct 19 23:06:57 radon kernel: [<ffffffffc04ddb9c>] ? xfsaild+0x16c/0x6f0
[xfs]
Oct 19 23:06:57 radon kernel: [<ffffffffc04d1e3c>] xfs_log_force+0x2c/0x70
[xfs]
Oct 19 23:06:57 radon kernel: [<ffffffffc04dda30>] ?
xfs_trans_ail_cursor_first+0x90/0x90 [xfs]
Oct 19 23:06:57 radon kernel: [<ffffffffc04ddb9c>] xfsaild+0x16c/0x6f0
[xfs]
Oct 19 23:06:57 radon kernel: [<ffffffffc04dda30>] ?
xfs_trans_ail_cursor_first+0x90/0x90 [xfs]
Oct 19 23:06:57 radon kernel: [<ffffffff810b098f>] kthread+0xcf/0xe0
Oct 19 23:06:57 radon kernel: [<ffffffff810b08c0>] ?
insert_kthread_work+0x40/0x40
Oct 19 23:06:57 radon kernel: [<ffffffff816b4f58>] ret_from_fork+0x58/0x90
Oct 19 23:06:57 radon kernel: [<ffffffff810b08c0>] ?
insert_kthread_work+0x40/0x40
Oct 19 23:06:57 radon kernel: INFO: task nfsd:1604 blocked for more than 120
seconds.
Eventually the system locks up completely.

Has anyone seen anything like this with these controllers and the latest kernel,
or have any ideas of what to look for?

						thanks,
						Noam

-----Original Message-----
From: CentOS [mailto:centos-bounces at centos.org] On Behalf Of Noam
Bernstein
Sent: Sunday, October 22, 2017 8:54 AM
To: CentOS mailing list <centos at centos.org>
Subject: [CentOS] Areca RAID controller on latest CentOS 7 (1708 i.e. RHEL
7.4) kernel 3.10.0-693.2.2.el7.x86_64
> Is anyone running any Areca RAID controllers with the latest CentOS 7
kernel,
> 3.10.0-693.2.2.el7.x86_64?  We recently updated (from 3.10.0-
> 514.26.2.el7.x86_64), and we?ve started having lots of problems.  To add to
> the confusion, there?s also a hardware problem (either with the controller
or
> the backplane most likely) that we?re in the process of analyzing. 
Regardless,
> we have an ARC1883i, and with the older kernel the system is stable, but
> with the new kernel it locks up within 1-12 hours of boot, with errors in
> /var/log/messages that start with things like
> kernel: arcmsr0: abort device command of scsi id = 0 lun = 0
> (that is indeed the RAID scsi device) and within a few minutes of those
also
> things like
> Oct 19 23:06:57 radon kernel: INFO: task xfsaild/dm-9:913 blocked for more
> than 120 seconds.
You mention you have hardware problems, what are they? A write is blocked
for longer than they host is willing to wait. There are a few sysctl parameters
that affect this but I'd be more willing to suggest its related to your
hardware
problems.

jlc