Re: Slow write times to gluster disk

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Hi Soumya,

When I originally did the tests I ran tcpdump on the client.

I have rerun the tests, doing tcpdump on the server

tcpdump -i any -nnSs 0 host 172.16.1.121 -w /root/capture_nfsfail.pcap

The results are in the same place

http://mseas.mit.edu/download/phaley/GlusterUsers/TestNFSmount/

capture_nfsfail.pcap   has the results from the failed touch experiment
capture_nfssucceed.pcap has the results from the successful touch experiment

The brick log files are there too.

I believe we are using kernel-NFS exporting a fuse mounted gluster volume. I am having Steve confirm this. I tried to find the fuse-mnt logs but failed. Where should I look for them?

Thanks

Pat



On 07/03/2017 07:58 AM, Soumya Koduri wrote:


On 06/30/2017 07:56 PM, Pat Haley wrote:

Hi,

I was wondering if there were any additional test we could perform to
help debug the group write-permissions issue?

Sorry for the delay. Please find response inline --


Thanks

Pat


On 06/27/2017 12:29 PM, Pat Haley wrote:

Hi Soumya,

One example, we have a common working directory dri_fleat in the
gluster volume

drwxrwsr-x 22 root dri_fleat     4.0K May  1 15:14 dri_fleat

my user (phaley) does not own that directory but is a member of the
group  dri_fleat and should have write permissions.  When I go to the
nfs-mounted version and try to use the touch command I get the following

ibfdr-compute-0-4(dri_fleat)% touch dum
touch: cannot touch `dum': Permission denied

One of the sub-directories under dri_fleat is "test" which phaley owns

drwxrwsr-x  2 phaley   dri_fleat 4.0K May  1 15:16 test

Under this directory (mounted via nfs) user phaley can write

ibfdr-compute-0-4(test)% touch dum
ibfdr-compute-0-4(test)%

I have put the packet captures in

http://mseas.mit.edu/download/phaley/GlusterUsers/TestNFSmount/

capture_nfsfail.pcap   has the results from the failed touch experiment
capture_nfssucceed.pcap  has the results from the successful touch
experiment

The command I used for these was

tcpdump -i ib0 -nnSs 0 host 172.16.1.119 -w /root/capture_nfstest.pcap

I hope these pkts were captured on the node where NFS server is running. Could you please use '-i any' as I do not see glusterfs traffic in the tcpdump.

Also looks like NFS v4 is used between client & nfs server. Are you using kernel-NFS here (i.e, kernel-NFS exporting fuse mounted gluster volume)? If that is the case please capture fuse-mnt logs as well. This error may well be coming from kernel-NFS itself before the request is sent to fuse-mnt process.

FWIW, we have below option -

Option: server.manage-gids
Default Value: off
Description: Resolve groups on the server-side.

I haven't looked into what this option exactly does. But it may worth testing with this option on.

Thanks,
Soumya



The brick log files are also in the above link.  If I read them
correctly they both funny times.  Specifically I see entries from
around 2017-06-27 14:02:37.404865  even though the system time was
2017-06-27 12:00:00.

One final item, another reply to my post had a link for possible
problems that could arise from users belonging to too many group. We
have seen the above problem even with a user belonging to only 4 groups.

Let me know what additional information I can provide.


Thanks

Pat


On 06/27/2017 02:45 AM, Soumya Koduri wrote:


On 06/27/2017 10:17 AM, Pranith Kumar Karampuri wrote:
The only problem with using gluster mounted via NFS is that it does not
respect the group write permissions which we need.

We have an exercise coming up in the a couple of weeks. It seems to me that in order to improve our write times before then, it would be good
to solve the group write permissions for gluster mounted via NFS now.
We can then revisit gluster mounted via FUSE afterwards.

What information would you need to help us force gluster mounted via
NFS
to respect the group write permissions?

Is this owning group or one of the auxiliary groups whose write
permissions are not considered? AFAIK, there are no special
permission checks done by gNFS server when compared to gluster native
client.

Could you please provide simple steps to reproduce the issue and
collect pkt trace and nfs/brick logs as well.

Thanks,
Soumya



--

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Pat Haley                          Email:  phaley@xxxxxxx
Center for Ocean Engineering       Phone:  (617) 253-6824
Dept. of Mechanical Engineering    Fax:    (617) 253-8125
MIT, Room 5-213                    http://web.mit.edu/phaley/www/
77 Massachusetts Avenue
Cambridge, MA  02139-4301

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