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CIFS (samba) access and unmounts suddenly glacially slow

cn flag
davidgo

(This was working fine until earlier today - but I've no idea what changed)

Whenever I try and mount a samba share across my LAN I am seeing the following - only on my Ubuntu 22.04 box [ ie the CIFS client built into VLC on my cellphone works fine ] -

  • Mounting is fast.

  • Attempts to access the SMB mount are generally extremely slow.

  • Doing a "df" is extremely slow - but only when a share is mounted. Doing a df with a share mounted takes fractionally over 1 minute - fairly consistently.

  • Unmounting is extremely slow.

  • When I do a "df -l" df is fast.

  • If instead of using SAMBA for sharing I use sshfs for the same resource it is fast.

  • Sometimes (it seems intermittent but I could not discern a pattern), accessing the SMB mount is fast.

  • Problem happens regardless of whether I use fstab or a manual mount command.

  • Problem persists with older kernels.

  • Problem persists with a new kernel in rescue mode.

  • Problem persists after upgrading the SMB server to Ubuntu 22.04

  • Problem persists regardless of the mount point.

  • Problem persists regardless of whether I use a wired or wireless connection.

  • Problem persists even when iptables firewall dropped.

I'm not sure how it is supposed to behave but when I use smbclient eg with a command like

 smbclient '//10.0.3.249/sharename'

It immediately returns some files, but then after a pause it gives me Error in dskattr: NT_STATUS_IO_TIMEOUT and associated message SMBecho failed (NT_STATUS_INVALID_NETWORK_RESPONSE). The connection is disconnected now.

I've tried adding client min protocol=core and client max protocol=SMB3 per https://stackoverflow.com/questions/68547105/nt-status-io-timeout-when-trying-to-connect-with-samba-client but no difference.

mtu on relevant interfaces for both boxes is 1500.

UPDATE: Problems with SMBCLIENT freezing appear even when issuing the commands from the server, and even when I use localhost rather then an IP.

There does not appear to be anything in the log file when I do an "ls" - even with logging verbosity turned up to 5.

UPDATE2

I noticed that when doing listings with SMBClient all the files in the root of the shared folder are being listed before the timeout - so this looks a bit more like a protocol error then a networking error.

I'm scratching my head on how to solve or even debug this. Any help would be appreciated.

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cn flag
davidgo
Very weirdly this problem went away by itself. No idea why. Maybe another device on the network was playing silly buggers, but I can't see how or why.
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