Hi,

the 0@lo is always there. It's used for some internal communication between the different modules.

(hen you don't have any OSTs in a lustre file system, you get an error "LustreError: 11-0: ... Communicating with 0@lo, operation mds_connect failed with -11" for which it is quite frequently asked here what that means)

On 07/08/2015 05:34 PM, Jérôme BECOT wrote:

Thanks for the tips

Everything is ok, I just have, and I don't know why, a connection listed as 0@lo when running lshowmount

Le 07/07/2015 09:27, Martin Hecht a écrit :

maybe this is what you are looking for:

during recovery on the MDS:
cat /proc/fs/lustre/mds/lustrefs-MDT0000/recovery_status"
shows the number of clients already connected and the number the server expects.

/proc/fs/lustre/mdt/lustre-MDT0000/recovery_status

during normal operation
cat /proc/fs/lustre/mds/lustrefs-MDT0000/num_exports
shows the number of exports (If I recall correctly, the MGS is a client as well in this context)

/proc/fs/lustre/mgs/MGS/num_exports
/proc/fs/lustre/mdt/lustre-MDT0000/num_exports

On 07/06/2015 05:16 PM, Scott Nolin wrote:

the 'lshowmount' command on the servers can do this.

However I sometimes have seen where lshowmount doesn't show any connected clients, but they obviously still are. So maybe there's a lower-level way than that utility that's better.

Scott

On 7/6/2015 10:09 AM, Jérôme BECOT wrote:

That's how i proceed, but i had kernel crashes on the MDS so I unmounted
and remounted it and it recovers

No way to check wether Lustre servers considers any client still connect
or not ?

Le 04/07/2015 04:43, Kurt Strosahl a écrit :

Hi,

I just did a clean shutdown/startup of two lustre file systems
last weekend (also for electrical work). The order that I've found
most effective is to first shutdown all the clients, then unmount the
osts/shutdown the oss systems, then unmount the mdt/mgs and shut down
that system. On the up I've found that turning on the mdt/mgs system,
letting it mount up. Then mounting the osts (my oss systems don't
mount lustre on boot). Once the last ost to be mounted looks like it
has finished any recovery it needs to do I mount a single client and
make sure it can see the entire system... and then go from there with
the rest of the clients.

Since all the lustre clients I have are in the same room as the lustre
file system itself I don't have to check for stray mounts (I just walk
around the room looking for systems that are still on, and then power
them off).

Good luck,
Kurt J. Strosahl
System Administrator
Scientific Computing Group, Thomas Jefferson National Accelerator
Facility

Message: 1
Date: Fri, 03 Jul 2015 13:49:32 +0200
From: J?r?me BECOT <jerome.becot@inserm.fr>
To: HPDD-discuss@ml01.01.org
Subject: [HPDD-discuss] Clean shutdown
Message-ID: <559676CC.1060009@inserm.fr>
Content-Type: text/plain; charset=utf-8; format=flowed

Hi there,

We are running a small lustre system (1MGS/MDS + 2 OSTs). I haven't
found the information, so i ask you :

What is the good order to shutdown the whole system (for electrical
maintenance ...) when you run a combined MGT/MDT :
- disconnect the clients
- is there any way to check if there is a client still connected ?
- unmount the MGT/MDT
- unmount the OSTs
- ... poweroff all the servers
- mount the OSTs
- then the MGT/MDT
- then the clients ?

or should I stop the ost first and mount them last ?

Thanks

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