xe sr-probe does not find NFSv4/NFSv4.1

[borzel]

Background:

• XCP-ng 7.6 (with all extras/testing packages up to date)
• FreeNAS-11.2-RELEASE-U1 as NFS-Server (NFSv4 enabled)

Steps:

1. enable NFSv4 on FreeNAS and reboot it to fully enable it (!)
   
2. Create new SR with XCP-ng Center (https:/xcp-ng/xenadmin/releases/tag/v7.6.3.21) with NFSv4.1 (or XenOrchestra -> this step just proves NFSv4.1 support)
   
3. Detach SR
4. run xe sr-probe type=nfs device-config:server=<some-ip> device-config:serverpath=/mnt/testpool/nfsv41test device-config:probeversion

Output of sr-probe

<?xml version="1.0" ?>
<SRlist>
        <SR>
                <UUID>2131f8f8-49be-0868-2b97-d624c9851584</UUID>
        </SR>
        <SR>
                <UUID>cce30ede-0fd2-b34a-04e5-291b56b9f8fc</UUID>
        </SR>
        <SupportedVersions>
                <Version>3</Version>
        </SupportedVersions>
</SRlist>

Expected result
Shows SupportedVersions 3, 4 and 4.1

[thctlo]

Hm getting :
Host Xen XCP 7.6.3 , NFSv4 enabled Server Debian 9.
exports file contains.
/srv/nfs4 192.168.xxx.0/24(rw,sync,fsid=0,crossmnt,no_subtree_check,sec=sys:krb5:krb5i:krb5p)
/srv/nfs4/xcphosts 192.168.xxx.0/24(rw,sync,no_subtree_check,sec=sys:krb5:krb5i:krb5p)

This current setup works for v3/v4/v4.1 with and without kerberos mounts.

xe sr-probe type=nfs device-config:server=IP_HERE device-config:serverpath=/xen/nfs-stor device-config:probeversion
Error code: SR_BACKEND_FAILURE_73
Error parameters: , NFS mount error [opterr=mount failed with return code 32],

[thctlo]

running : xe sr-probe type=nfs device-config:server=IP_HERE device-config:probeversion

Error code: SR_BACKEND_FAILURE_101
Error parameters: , The request is missing the serverpath parameter, <?xml version="1.0" ?>
<nfs-exports>
<Export>
<Target>192.168.xxx.xxx</Target>
<Path>/srv/nfs4/xcphosts</Path>
<Accesslist>192.168.xxx.0/24</Accesslist>
</Export>
<Export>
<Target>192.168.xxx.xxx</Target>
<Path>/srv/nfs4</Path>
<Accesslist>192.168.xxx.0/24</Accesslist>
</Export>
</nfs-exports>

[stormi]

@borzel Is that a problem that occurs for any NFS share that supports NFS 4 or above, or only with specific servers?

[NormHenderson]

Not sure if it is related to the same root cause however: when xe sr-create specifies only type=nfs, it defaults to NFSv3 and will not negotiate NFSv4/NFSv4.1 share without adding device-config:nfsversion=4.1 (which isn't documented as far as I can tell). IMHO it should be starting with NFSv4.1 and negotiating downwards. (XCP-ng 8.1 connecting to nfs-kernel-server on Ubuntu 20.04)

[ondraknezour]

I had similar problem with FreeBSD NFS server set up with minimal NFS version 4 (vfs.nfsd.server_min_nfsvers=4 in the /etc/sysctl.conf file) [1].

I was told [2], that NFS v4 doesn't use RPC, so if support for older protocol version isn't needed, nfsd would not register with rcpbind, making function check_server_service in /opt/xensource/sm/nfs.py unreliable and invalid, because it checks for condition (nfs service in rpcinfo -s output) which is not always present.

[1] https://lists.freebsd.org/pipermail/freebsd-net/2021-January/057371.html
[2] https://lists.freebsd.org/pipermail/freebsd-net/2021-January/057372.html

[jcharaoui]

I've hit this bug with an NFSv4+ only server (eg. NFSv3 is disabled). XCP-ng is unable to add the SR because it depends on the presence of NFSv3 services.

[olivierlambert]

Then I think it should be reported upstream ASAP :)

https:/xapi-project/sm/issues

[TristisOris]

still actual for Huawei storage.

[olivierlambert]

IIRC, this was fixed in a recent upstream SMAPI patch (but likely not yet available in XCP-ng. @stormi can you take a look where you are around? Thanks!

[stormi]

I don't remember commits that would address this, and the issue on the upstream repository got no answers from the devs.

Recent commits that are about NFS in sm are: xapi-project/sm@e121864 and xapi-project/sm@6fbff68 but I don't think they are related to this issue here.

[emanzx]

Any update on this? I have checked that the upstream already push a fix for this issues. but when I update my XCP-ng installation the file still not updated. So I take my own way and just replaced the driver file for NFSSR.py and nfs.py with the update. but still not working and xpc-ng center just giving me this error.

I really need NFS V4 to work as PETASAN instance only support NFS v4 and above for their NFS exports. Thanks.

[benjamreis]

Hi!

The fix wasn't available in XCP-ng 8.2.1, it'll be released soon but if you want to test it in advance: yum update sm sm-rawhba --enablerepo=xcp-ng-ci

Bear in mind it is a test build so not safe to run in production.
Regards :)

[emanzx]

Hi!

The fix wasn't available in XCP-ng 8.2.1, it'll be released soon but if you want to test it in advance: yum update sm sm-rawhba --enablerepo=xcp-ng-ci

Bear in mind it is a test build so not safe to run in production. Regards :)

Thanks for the update. I will try it with my test server. may I know when the next update that the fix will be commited?

[benjamreis]

It's currently in the CI phase of our pipeline, so if everything goes smoothly I'd say a couple weeks.
More if we find issues.

[viniciusferrao]

Any news on this one? I was actually surprised to see that NFSv4 only servers are an issue because XCP-ng manual states that NFS is preferred instead of iSCSI.

So I started the planning to move away from iSCSI and stumbled upon this issue.

[NormHenderson]

@viniciusferrao I had a very bad experience with XCP-ng storage on iSCSI. For the last 3 years I have been using nfs 4.1 without any real difficulties (some performance concerns when VMs boot and until they stabilize, but I was never able to narrow down the cause). I am on XCP-ng v.8.2 which has the option to select nfs v3 v4 or v4.1 when creating a new nfs SR. I also use option "hard" which has pros and cons, there are other threads here on that subject.

[viniciusferrao]

@viniciusferrao I had a very bad experience with XCP-ng storage on iSCSI. For the last 3 years I have been using nfs 4.1 without any real difficulties (some performance concerns when VMs boot and until they stabilize, but I was never able to narrow down the cause). I am on XCP-ng v.8.2 which has the option to select nfs v3 v4 or v4.1 when creating a new nfs SR. I also use option "hard" which has pros and cons, there are other threads here on that subject.

But is there any workaround today? Because I tried to mount the volume and was affected by the issue on this ticket.

My XCP-ng dates back to 2013 when I originally installed XenServer 6.2. I've been updating it since then. The same for the storage system that's FreeNAS (at the time) and now TrueNAS. The disk pool was created in early 2014. Since the beginning, this pool is iSCSI and I had very expensive workloads on it, like Exchange 2010 and later 2013 with 700 user accounts, more than a TB of iSCSI mailboxes on top of XenServer virtual disks.

And now I was moving to NFS, due to the cited recommendation and I'm unable to.

How to mount the NFS share? What's the workaround? TrueNAS does not enables NFSv3 and v4 at the same time.

Thanks.

[NormHenderson]

For me, it was just in Xen Orchestra:
select the pool
SR - create a new SR
Select storage type: NFS
Settings: Server (your NFS path) NFS version 4.1 NFS options (in my case, study the implications) hard
Similar process in XCP-ng Center.

However your question makes me wonder if you are even talking about an XCP-ng storage repositiory - possibly connecting to an NFS server from a VM? I do that too, from Linux at least it's standard mount -t nfs4, no magic.

[viniciusferrao]

For me, it was just in Xen Orchestra: select the pool SR - create a new SR Select storage type: NFS Settings: Server (your NFS path) NFS version 4.1 NFS options (in my case, study the implications) hard Similar process in XCP-ng Center.

However your question makes me wonder if you are even talking about an XCP-ng storage repositiory - possibly connecting to an NFS server from a VM? I do that too, from Linux at least it's standard mount -t nfs4, no magic.

Yeah, this does not work. I'm affected by the bug on this thread. I thought you had a workaround for it. Your NFS server probably supports NFSv3 and v4 at the same time, which isn't my case.

[stormi]

Yes, the issue is when the NFS server doesn't advertise what it supports through rpcbind, which is a v3-only thing (rpcbing can report, although is not obligated to do so, also v4.x protocol versions, which explains why some users can select v4.x protocols when their server also supports v3).

We do have a fix for this, it is build, and is currently on a pre-release repository before it can be released to all users.

On XCP-ng 8.2, you can try it with:

yum update sm sm-rawhba --enablerepo=xcp-ng-ci,xcp-ng-testing,xcp-ng-candidates

Internal CI tests already ran successfully.

On XCP-ng 8.3, it should be already supported.

[viniciusferrao]

Yes, the issue is when the NFS server doesn't advertise what it supports through rpcbind, which is a v3-only thing (rpcbing can report, although is not obligated to do so, also v4.x protocol versions, which explains why some users can select v4.x protocols when their server also supports v3).

We do have a fix for this, it is build, and is currently on a pre-release repository before it can be released to all users.

On XCP-ng 8.2, you can try it with:

yum update sm sm-rawhba --enablerepo=xcp-ng-ci,xcp-ng-testing,xcp-ng-candidates

Internal CI tests already ran successfully.

On XCP-ng 8.3, it should be already supported.

Thank you @stormi. But may I ask if there's any timeline to it lands on stable channels? On 8.2.1 or 8.3?

[stormi]

On 8.2, it will go with the next train of updates, which is not scheduled yet. A few weeks maybe. It's already in XCP-ng 8.3, but 8.3 itself is still a (rather stable) beta.