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Basic Troubleshooting

Logs

The correct set of log file to collect depends on the nature of the problem. If unsure, then it is best to collect log files for all Mayastor containers. In nearly every case, the logs of all of the control plane component pods will be needed;
  • csi-controller
  • core-agent
  • rest
  • msp-operator
List all Mayastor pods
Output example
kubectl -n mayastor get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
mayastor-csi-7pg82 2/2 Running 0 15m 10.0.84.131 worker-2 <none> <none>
mayastor-csi-gmpq6 2/2 Running 0 15m 10.0.239.174 worker-1 <none> <none>
mayastor-csi-xrmxx 2/2 Running 0 15m 10.0.85.71 worker-0 <none> <none>
mayastor-qgpw6 1/1 Running 0 14m 10.0.85.71 worker-0 <none> <none>
mayastor-qr84q 1/1 Running 0 14m 10.0.239.174 worker-1 <none> <none>
mayastor-xhmj5 1/1 Running 0 14m 10.0.84.131 worker-2 <none> <none>
... etc (output truncated for brevity)

Mayastor pod log file

Mayastor containers form the data plane of a Mayastor deployment. A cluster should schedule as many mayastor container instances as required storage nodes have been defined. This log file is most useful when troubleshooting I/O errors however, provisioning and management operations might also fail because of a problem on a storage node.
Example obtaining mayastor
kubectl -n mayastor logs mayastor-qgpw6 mayastor

CSI agent pod log file

If experiencing problems with (un)mounting a volume on an application node, this log file can be useful. Generally all worker nodes in the cluster will be configured to schedule a mayastor CSI agent pod, so it's good to know which specific node is experiencing the issue and inspect the log file only for that node.
Example obtaining mayastor CSI driver
kubectl -n mayastor logs mayastor-csi-7pg82 mayastor-csi

CSI sidecars

These containers implement the CSI spec for Kubernetes and run within the same pods as the csi-controller and mayastor-csi (node plugin) containers. Whilst they are not part of Mayastor's code, they can contain useful information when a Mayastor CSI controller/node plugin fails to register with k8s cluster.
Obtaining CSI control containers logs
kubectl -n mayastor logs $(kubectl -n mayastor get pod -l app=moac -o jsonpath="{.items[0].metadata.name}") csi-attacher
kubectl -n mayastor logs $(kubectl -n mayastor get pod -l app=moac -o jsonpath="{.items[0].metadata.name}") csi-provisioner
Example obtaining CSI node container log
kubectl -n mayastor logs mayastor-csi-7pg82 csi-driver-registrar

Coredumps

A coredump is a snapshot of process' memory combined with auxiliary information (PID, state of registers, etc.) and saved to a file. It is used for post-mortem analysis and it is generated automatically by the operating system in case of a severe, unrecoverable error (i.e. memory corruption) causing the process to panic. Using a coredump for a problem analysis requires deep knowledge of program internals and is usually done only by developers. However, there is a very useful piece of information that users can retrieve from it and this information alone can often identify the root cause of the problem. That is the stack (backtrace) - a record of the last action that the program was performing at the time when it crashed. Here we describe how to get it. The steps as shown apply specifically to Ubuntu, other linux distros might employ variations.
We rely on systemd-coredump that saves and manages coredumps on the system, coredumpctl utility that is part of the same package and finally the gdb debugger.
Install systemd-coredump and gdb
sudo apt-get install -y systemd-coredump gdb lz4
If installed correctly then the global core pattern will be set so that all generated coredumps will be piped to the systemd-coredump binary.
Verify coredump configuration
Output example
cat /proc/sys/kernel/core_pattern
|/lib/systemd/systemd-coredump %P %u %g %s %t 9223372036854775808 %h
List coredumps
Output example
coredumpctl list
TIME PID UID GID SIG COREFILE EXE
Tue 2021-03-09 17:43:46 UTC 206366 0 0 6 present /bin/mayastor
If there is a new coredump from the mayastor container, the coredump alone won't be that useful. GDB needs to access the binary of crashed process in order to be able to print at least some information in the backtrace. For that, we need to copy the contents of the container's filesystem to the host.
Get ID of the mayastor container
Output example
docker ps | grep mayadata/mayastor
b3db4615d5e1 mayadata/mayastor "sleep 100000" 27 minutes ago Up 27 minutes k8s_mayastor_mayastor-n682s_mayastor_51d26ee0-1a96-44c7-85ba-6e50767cd5ce_0
d72afea5bcc2 mayadata/mayastor-csi "/bin/mayastor-csi -…" 7 hours ago Up 7 hours k8s_mayastor-csi_mayastor-csi-xrmxx_mayastor_d24017f2-5268-44a0-9fcd-84a593d7acb2_0
Copy relevant parts of the container
mkdir -p /tmp/rootdir
docker cp b3db4615d5e1:/bin /tmp/rootdir
docker cp b3db4615d5e1:/nix /tmp/rootdir
Now we can start GDB. Don't use the coredumpctl command for starting the debugger. It invokes GDB with invalid path to the debugged binary hence stack unwinding fails for Rust functions. At first we extract the compressed coredump.
Find location of the compressed coredump
Output example
coredumpctl info | grep Storage | awk '{ print $2 }'
/var/lib/systemd/coredump/core.mayastor.0.6a5e550e77ee4e77a19bd67436ce7a98.64074.1615374302000000000000.lz4
Extract the coredump
sudo lz4cat /var/lib/systemd/coredump/core.mayastor.0.6a5e550e77ee4e77a19bd67436ce7a98.64074.1615374302000000000000.lz4 >core
Open coredump in GDB
Output example
gdb -c core /tmp/rootdir$(readlink /tmp/rootdir/bin/mayastor)
GNU gdb (Ubuntu 9.2-0ubuntu1~20.04) 9.2
Copyright (C) 2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Type "show copying" and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
[New LWP 13]
[New LWP 17]
[New LWP 14]
[New LWP 16]
[New LWP 18]
Core was generated by `/bin/mayastor -l0 -nnats'.
Program terminated with signal SIGABRT, Aborted.
#0 0x00007ffdad99fb37 in clock_gettime ()
[Current thread is 1 (LWP 13)]
Once in GDB we need to set a sysroot so that GDB knows where to find the binary for the debugged program.
Set sysroot in GDB
Output example
set auto-load safe-path /tmp/rootdir
set sysroot /tmp/rootdir
Reading symbols from /tmp/rootdir/nix/store/f1gzfqq10dlha1qw10sqvgil34qh30af-systemd-246.6/lib/libudev.so.1...
(No debugging symbols found in /tmp/rootdir/nix/store/f1gzfqq10dlha1qw10sqvgil34qh30af-systemd-246.6/lib/libudev.so.1)
Reading symbols from /tmp/rootdir/nix/store/0kdiav729rrcdwbxws653zxz5kngx8aa-libspdk-dev-21.01/lib/libspdk.so...
Reading symbols from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libdl.so.2...
(No debugging symbols found in /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libdl.so.2)
Reading symbols from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libgcc_s.so.1...
(No debugging symbols found in /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libgcc_s.so.1)
Reading symbols from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libpthread.so.0...
...
After that we can print backtrace(s).
Obtain backtraces for all threads in GDB
Output example
thread apply all bt
Thread 5 (Thread 0x7f78248bb640 (LWP 59)):
#0 0x00007f7825ac0582 in __lll_lock_wait () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libpthread.so.0
#1 0x00007f7825ab90c1 in pthread_mutex_lock () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libpthread.so.0
#2 0x00005633ca2e287e in async_io::driver::main_loop ()
#3 0x00005633ca2e27d9 in async_io::driver::UNPARKER::{{closure}}::{{closure}} ()
#4 0x00005633ca2e27c9 in std::sys_common::backtrace::__rust_begin_short_backtrace ()
#5 0x00005633ca2e27b9 in std::thread::Builder::spawn_unchecked::{{closure}}::{{closure}} ()
#6 0x00005633ca2e27a9 in <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once ()
#7 0x00005633ca2e26b4 in core::ops::function::FnOnce::call_once{{vtable-shim}} ()
#8 0x00005633ca723cda in <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once () at /rustc/d1206f950ffb76c76e1b74a19ae33c2b7d949454/library/alloc/src/boxed.rs:1546
#9 <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once () at /rustc/d1206f950ffb76c76e1b74a19ae33c2b7d949454/library/alloc/src/boxed.rs:1546
#10 std::sys::unix::thread::Thread::new::thread_start () at /rustc/d1206f950ffb76c76e1b74a19ae33c2b7d949454//library/std/src/sys/unix/thread.rs:71
#11 0x00007f7825ab6e9e in start_thread () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libpthread.so.0
#12 0x00007f78259e566f in clone () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libc.so.6
Thread 4 (Thread 0x7f7824cbd640 (LWP 57)):
#0 0x00007f78259e598f in epoll_wait () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libc.so.6
#1 0x00005633ca2e414b in async_io::reactor::ReactorLock::react ()
#2 0x00005633ca583c11 in async_io::driver::block_on ()
#3 0x00005633ca5810dd in std::sys_common::backtrace::__rust_begin_short_backtrace ()
#4 0x00005633ca580e5c in core::ops::function::FnOnce::call_once{{vtable-shim}} ()
#5 0x00005633ca723cda in <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once () at /rustc/d1206f950ffb76c76e1b74a19ae33c2b7d949454/library/alloc/src/boxed.rs:1546
#6 <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once () at /rustc/d1206f950ffb76c76e1b74a19ae33c2b7d949454/library/alloc/src/boxed.rs:1546
#7 std::sys::unix::thread::Thread::new::thread_start () at /rustc/d1206f950ffb76c76e1b74a19ae33c2b7d949454//library/std/src/sys/unix/thread.rs:71
#8 0x00007f7825ab6e9e in start_thread () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libpthread.so.0
#9 0x00007f78259e566f in clone () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libc.so.6
Thread 3 (Thread 0x7f78177fe640 (LWP 61)):
#0 0x00007f7825ac08b7 in accept () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libpthread.so.0
#1 0x00007f7825c930bb in socket_listener () from /tmp/rootdir/nix/store/0kdiav729rrcdwbxws653zxz5kngx8aa-libspdk-dev-21.01/lib/libspdk.so
#2 0x00007f7825ab6e9e in start_thread () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libpthread.so.0
#3 0x00007f78259e566f in clone () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libc.so.6
Thread 2 (Thread 0x7f7817fff640 (LWP 60)):
#0 0x00007f78259e598f in epoll_wait () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libc.so.6
#1 0x00007f7825c7f174 in eal_intr_thread_main () from /tmp/rootdir/nix/store/0kdiav729rrcdwbxws653zxz5kngx8aa-libspdk-dev-21.01/lib/libspdk.so
#2 0x00007f7825ab6e9e in start_thread () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libpthread.so.0
#3 0x00007f78259e566f in clone () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libc.so.6
Thread 1 (Thread 0x7f782559f040 (LWP 56)):
#0 0x00007fff849bcb37 in clock_gettime ()
#1 0x00007f78259af1d0 in clock_gettime@GLIBC_2.2.5 () from /tmp/rootdir/nix/store/a6rnjp15qgp8a699dlffqj94hzy1nldg-glibc-2.32/lib/libc.so.6
#2 0x00005633ca23ebc5 in <tokio::park::either::Either<A,B> as tokio::park::Park>::park ()
#3 0x00005633ca2c86dd in mayastor::main ()
#4 0x00005633ca2000d6 in std::sys_common::backtrace::__rust_begin_short_backtrace ()
#5 0x00005633ca2cad5f in main ()

Diskpool behaviour

The below behaviour may be encountered while uprading from older releases to Mayastor 2.4 release and above.

Get Dsp

Running kubectl get dsp -n mayastor could result in the error due to the v1alpha1 schema in the discovery cache. To resolve this, run the command kubectl get diskpools.openebs.io -n mayastor. After this kubectl discovery cache will be updated with v1beta1 object for dsp.

Create API

When creating a Disk Pool with kubectl create -f dsp.yaml, you might encounter an error related to v1alpha1 CR definitions. To resolve this, ensure your CR definition is updated to v1beta1 in the YAML file (for example, apiVersion: openebs.io/v1beta1).
You can validate the schema changes by executing kubectl get crd diskpools.openebs.io.