Sympl server running slowly

Problem Description

In what seems to be a repeat of my previous topic (Slow sending and receiving of email ), one of my Sympl servers is again running incredibly slowly, e.g.

  • Emails taken 30+ seconds to send (in Thunderbird and Neomutt, so I don’t think it’s a client problem)
  • IMAP logins take a similarly long time
  • Websites are slow to respond
  • Running commands via sudo has a noticeable delay (5+ seconds)

Basically it’s as if everything on the server is running slower than usual, taking 5-30+ seconds to respond instead of more or less instantly. My other Sympl server is working fine.

I can’t work out what the problem is. I’ve looked at the following:

  • Load average is negligible (0.1 or less)
  • 75% of the RAM is free
  • No swap in use
  • Both CPU cores are at <1% usage
  • No users logged in other than me (I’m the only one with access)
  • No suspicious processes

Things I’ve tried so far:

  • Disabling unnecessary services - this seems to break monitoring and causes more problems.
  • Upgrading from VPS 2 to 4, which increases the RAM from 2GB to 4GB
  • Removing allow rules from the firewall for services I never use (e.g. POP3)

Can anyone suggest anything else I can try please? Although I can still use the server, it’s for my business so websites loading slowly etc. looks really bad.

Any Error Messages

I’ve noticed this warning repeats itself in the log:

Jul 13 09:38:31 borusa dovecot: auth-worker(3371): Warning: read(/run/dovecot/sympl-mail-dict-proxy): dict lookup took 5.013 secs (5.013 in dict wait, 0.000 in other ioloops, 0.000 in locks): Lshared/passdb/paul@phpdeveloper.org.uk

Environment

  • Sympl Version [9.0/10.0]: 10.0
  • Sympl Testing Version? [Yes/No] No
  • Debian Version [Buster/Stretch]: Buster
  • Hardware Type? [Dedicated/Virtual/Pi] Virtual
  • Hosted On? [name of hosting co] Mythic Beasts

There’s a few things it could be, but the only one which makes sense would be if DNS resolution on the server itself was unhappy, as a lot of the things you mention tend to do reverse DNS lookups for logging purposes.

However, this doesn’t entirely sound like a Sympl problem, but I’ll message you privately so I can take a look…

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