Hi -
We've been having strange performance problems for over a year on high
powered workstations with fast (10Gb) networking. Programs that run
instantly on user's laptops would take 5-10 minutes to even launch on
these dual Xeon workstations with 128GB of RAM. The OS is Ubuntu 18.04
Last week I finally tracked this down to a comedy of errors, the first
involving autofs. We only use NFS v.4.x, and thanks to a tip from Ian
Kent, I had added:
mount_nfs_default_protocol = 4
to /etc/autofs.conf. However, using this setting in /etc/auto.home:
* octopus.biosci.utexas.edu:/home/&
any attempt to access a non-existent directory in /home (e.g.
/home/syslog) would result in the automounter hanging while various
attempts to mount were executed. Changing the auto.home line to
* -tcp,vers=4.2 octopus.biosci.utexas.edu:/home/&
resolved this issue. I can understand the tcp option, but what doesn't
make sense to me is the necessity to also specify vers=4.2
If I remove vers=4.2 from the options list, the automounter starts
hanging again when asked to mount a non-existent directory.
Maybe this is just an issue with mount.nfs?
This isn't relevant to autofs, but to satisfy the curious, the next
obvious question is why on earth were people attempting to mount
non-existent directories in /home, and the answer is (in part) some
negligent Debian package management. After sifting through strace
output I noticed entries like this in /etc/passwd:
syslog:x:102:106::/home/syslog:/usr/sbin/nologin
I guess they were thinking that since no one can log in as syslog, it
doesn't matter what the home directory is set to; likely someone who
doesn't use or perhaps even know about autofs. On my Arch systems these
entries would look like this:
syslog:x:102:106::/:/usr/sbin/nologin
The final piece of the puzzle is why on earth do misconfigured entries
in /etc/passwd come in to play, and the answer is anaconda/miniconda. A
lot of computational biology tools are embedded in conda environments,
and for some frankly inexplicable reason conda likes to troll through
/etc/passwd searching for environments. This seems like an anachronism
from the days when all real users were documented in /etc/passwd rather
than via some LDAP, AD, NIS, or Kerberos directory server.
