I have tried to find a network error but can't see anything. Every node
I've tested has the same (and correct) view of things.
_On node cn7:_ (the problematic one)
em1: link/ether 50:9a:4c:79:31:4d inet 10.28.3.137/24
_On login machine:_
[alex@li1 ~]$ host cn7
cn7.ydesign.se has address 10.28.3.137
[alex@li1 ~]$ arp cn7
Address HWtype HWaddress Flags
Mask Iface
cn7.ydesign.se ether 50:9a:4c:79:31:4d C em1
_On slurmctld machine:_
[alex@cmgr1 ~]$ host cn7
cn7.ydesign.se has address 10.28.3.137
[alex@cmgr1 ~]$ arp cn7
Address HWtype HWaddress Flags
Mask Iface
cn7.ydesign.se ether 50:9a:4c:79:31:4d C em1
Yes, I have seen your pages and must say that they have been pure gold
on many occasions, thanks a lot Ole! But our cluster is still tiny and
the whole cluster is located in its own network segment. The number of
ARP entries is far from 512 (actually, more like ~30).
I just don't understand why sbatch works but not srun?
Could this be some error in the state files perhaps? Something that
maybe got corrupted when the node (cn7) unexpectedly died?
Regards,
Alexander
Den 2019-05-29 kl. 15:12, skrev Ole Holm Nielsen:
Hi Alexander,
The error "can't find address for host cn7" would indicate a DNS
problem. What is the output of "host cn7" from the srun host li1?
How many network devices are in your subnet? It may be that the Linux
kernel is doing "ARP cache trashing" if the number of devices
approaches 512. What is the result of "arp cn7"?
To fix ARP cache trashing look in my Slurm Wiki page
https://wiki.fysik.dtu.dk/niflheim/Slurm_configuration#configure-arp-cache-for-large-networks
Best regards,
Ole
On 5/29/19 3:00 PM, Alexander Åhman wrote:
Hi,
Have a very strange problem. The cluster has been working just fine
until one node died and now I can't submit jobs to 2 of the nodes
using srun from the login machine. Using sbatch works just fine and
also if I use srun from the same host as slurmctld.
All the other nodes works just fine as they always has, only 2 nodes
are experiencing this problem. Very strange...
Have checked network connectivity and DNS and that is OK. I can ping,
ssh to all nodes just fine. All nodes are identical and using Slurm
18.08.
Also tested to reboot the 2 nodes and slurmctld but still same problem.
[alex@li1 ~]$ srun -w cn7 hostname
srun: error: fwd_tree_thread: can't find address for host cn7, check
slurm.conf
srun: error: Task launch for 1088816.0 failed on node cn7: Can't find
an address, check slurm.conf
srun: error: Application launch failed: Can't find an address, check
slurm.conf
srun: Job step aborted: Waiting up to 32 seconds for job step to finish.
srun: error: Timed out waiting for job step to complete
[alex@li1 ~]$ srun -w cn6 hostname
cn6.ydesign.se
What is this error "can't find address for host" about? Have searched
the web but can't find any good information about what the problem is
or what to do to resolve it.
Any kind soul out there who knows what to do next?
