[Samba] How to diagnose a busy LDAP server process in the Samba AD DC

Mon Mar 25 16:30:00 UTC 2024

Hello Andrew,

What's the explanation for when the log level is set to 5, the error
NT_STATUS_IO_TIMEOUT doesn't appear, but when it's at the default log
level, it does?

On Mon, Mar 18, 2024 at 10:33 AM Elias Pereira <empbilly at gmail.com> wrote:

> hi Andrew, thanks for the help!!!
>
> It seems to me the LDAP process being busy would be the root cause here.
>> Working out what is going on here shouldn't is a detective task - I always
>> start with a wireshark trace.  The client making all the noise/traffic will
>> be the one causing the trouble.
>
>
> In the wireshark analysis, should I filter only by the ldap protocol or
> leave everything? Should I look at something specific in the client logs?
>
> On Sun, Mar 10, 2024 at 9:31 PM Andrew Bartlett <abartlet at samba.org>
> wrote:
>
>> Thanks for getting back to me.
>>
>> It seems to me the LDAP process being busy would be the root cause here.
>> Working out what is going on here shouldn't is a detective task - I always
>> start with a wireshark trace.  The client making all the noise/traffic will
>> be the one causing the trouble.
>>
>> If it isn't clear from that, then look into the DB audit logging for
>> perhaps busy writes
>>
>>
>> https://wiki.samba.org/index.php/Setting_up_Audit_Logging#Enabling_AD_DC_Database_Audit_Logging
>>
>> Finally, set 'log level = 5' and look for logs like: LDAP Query:
>> Duration was
>>
>> This will tell you about how long each query is taking, potentially
>> showing a particularly slow query that needs to be stopped.
>>
>> Andrew Bartlett
>>
>> On Sun, 2024-03-10 at 19:46 -0300, Elias Pereira wrote:
>>
>> Is the drepl local processes very busy doing inbound replication?
>>
>>
>> How can I check this?
>>
>> My instinct is either the server is very busy (and this should show up in
>> CPU use) or a transaction is being held open excessively.
>>
>>
>> I use VMs on Proxmox. In DC1, I installed the Proxmox agent, and CPU
>> usage via the dashboard is very low. However, when I checked using 'top,'
>> the LDAP process is consuming around 94/96% of the CPU. Very strange.
>>
>>
>> It is probably 94% of a single CPU, but you might have 8 CPUs in the VM,
>> so overall use is low.
>>
>> The VM has 4 CPUs and 6GB of memory.
>>
>>
>>
>> On Sun, Mar 10, 2024 at 5:55 PM Andrew Bartlett <abartlet at samba.org>
>> wrote:
>>
>> Either the local server is busy, or possibly (but it would not explain
>> the samba_kcc) Samba's drepl process is stuck talking to a remote server.
>>
>> Is the drepl local processes very busy doing inbound replication?
>>
>> My instinct is either the server is very busy (and this should show up in
>> CPU use) or a transaction is being held open excessively.
>>
>> Andrew Bartlett
>>
>> On Sat, 2024-03-09 at 19:11 -0300, Elias Pereira via samba wrote:
>>
>> I've been grappling with a recurring set of errors for quite some time now:
>>
>> - UpdateRefs failed with NT_STATUS_IO_TIMEOUT
>>
>> - Failed samba_kcc - NT_STATUS_IO_TIMEOUT
>>
>> - IRPC callback failed for DsReplicaSync - NT_STATUS_IO_TIMEOUT
>>
>>
>> Despite cranking up the log level to 10, the returned information remains
>>
>> frustratingly cryptic and hard to decipher.
>>
>>
>> This error, being overly generic, continues to elude identification even
>>
>> with
>>
>> the heightened log verbosity. The challenge lies in tracing its origin.
>>
>>
>> Running samba-tool dbcheck doesn't reveal any problems, yet executing the
>>
>> command while monitoring the Samba log with "tail -f" exposes errors
>>
>> identical
>>
>> to those described above.
>>
>>
>> Interestingly, samba-tool drs showrepl doesn't report any errors.
>>
>>
>> So, what additional steps can be taken to unearth the root cause
>>
>> of these persistent NT_STATUS_IO_TIMEOUT errors?
>>
>>
>>
>> On Fri, Mar 1, 2024 at 10:32 PM Elias Pereira <
>>
>> empbilly at gmail.com
>>
>> > wrote:
>>
>>
>> There is probably nothing wrong with your log, but Firefox doesn't
>>
>> like it, it thinks it contains a virus.
>>
>>
>>
>> I just saw now that your response ended up in spam, probably because of
>>
>> the link with the log. O.o
>>
>>
>> I still receive the error in the logs:
>>
>> source4/dsdb/kcc/kcc_periodic.c:790: Failed samba_kcc -
>>
>> NT_STATUS_IO_TIMEOUT
>>
>>
>> The strangest thing is that it occurs when the command is executed:
>>
>> samba-tool dbcheck --cross-ncs --fix --yes
>>
>>
>> Could it be some object causing this error?
>>
>>
>> On Mon, Feb 12, 2024 at 4:40 PM Rowland Penny via samba <
>>
>> samba at lists.samba.org
>>
>> > wrote:
>>
>>
>> On Mon, 12 Feb 2024 16:20:27 -0300
>>
>> Elias Pereira via samba <
>>
>> samba at lists.samba.org
>>
>> > wrote:
>>
>>
>> hi,
>>
>>
>> My saga continues...
>>
>>
>> I've configured the audit log for drs_repl in smb.conf, and below is
>>
>> the log generated.
>>
>> https://transfer.sh/7fen4qCNIQ/drs_repl.log
>>
>>
>>
>> The log level was 5.
>>
>> drs_repl:5@/var/log/samba/drs_repl.log
>>
>>
>> Could someone take a look and help me understand the log?
>>
>>
>>
>> There is probably nothing wrong with your log, but Firefox doesn't
>>
>> like it, it thinks it contains a virus.
>>
>>
>> Rowland
>>
>>
>>
>>
>> --
>>
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>>
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>>
>>
>>
>>
>>
>> --
>>
>> Elias Pereira
>>
>>
>>
>>
>> --
>>
>> Elias Pereira
>>
>> --
>>
>>
>> Andrew Bartlett (he/him)       https://samba.org/~abartlet/
>> Samba Team Member (since 2001) https://samba.org
>> Samba Team Lead                https://catalyst.net.nz/services/samba
>> Catalyst.Net Ltd
>>
>> Proudly developing Samba for Catalyst.Net Ltd - a Catalyst IT group
>> company
>>
>> Samba Development and Support: https://catalyst.net.nz/services/samba
>>
>> Catalyst IT - Expert Open Source Solutions
>>
>>
>>
>>
>> --
>> Elias Pereira
>>
>> --
>>
>> Andrew Bartlett (he/him)       https://samba.org/~abartlet/
>> Samba Team Member (since 2001) https://samba.org
>> Samba Team Lead                https://catalyst.net.nz/services/samba
>> Catalyst.Net Ltd
>>
>> Proudly developing Samba for Catalyst.Net Ltd - a Catalyst IT group
>> company
>>
>> Samba Development and Support: https://catalyst.net.nz/services/samba
>>
>> Catalyst IT - Expert Open Source Solutions
>>
>>
>>
>
> --
> Elias Pereira
>

-- 
Elias Pereira