[systemd-devel] Antw: [EXT] Re: Journald retaining logs for only 10 days

[Ulrich Windl]

>>> Vito Caputo <vcaputo at pengaru.com> schrieb am 14.11.2020 um 21:29 in
Nachricht
<20201114202930.x7wbx4p37bkkwona at shells.gnugeneration.com>:
> On Sat, Nov 14, 2020 at 09:31:23AM +0000, Nikolaus Rath wrote:
>> Hello,
>> 
>> I just discovered that on one of my systems journald only retains log
>> entries for about 10 days:
>> 
>> # journalctl | head ‑1
>> ‑‑ Logs begin at Wed 2020‑11‑04 15:57:13 UTC, end at Sat 2020‑11‑14
09:28:19 UTC. ‑‑
>> 
>> I do not understand what could cause this, because I have no retention
>> limit configured, and the logs take up way less space than I have
>> reserved:
>> 
>> # journalctl ‑‑disk‑usage
>> Archived and active journals take up 320.0M in the file system.
>> 
>> # journalctl > alllogs
>> # ls ‑lh alllogs 
>> ‑rw‑r‑‑r‑‑ 1 root root 27M Nov 14 09:24 alllogs
>> 
>> 
>> Can someone help me understand where the log entries have gone?
>> 
>> # journalctl ‑‑version
>> systemd 241 (241)
>> +PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP 
> +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD ‑IDN2 +IDN
‑PCRE2 
> default‑hierarchy=hybrid
>> 
>> # grep ‑vE '^#' /etc/systemd/journald.conf 
>> 
>> [Journal]
>> SystemMaxUse=300M
>> 
>> 
> 
> One thing to consider is journald allocates space per‑file in 8MiB
> increments.

Why that? Because disk space is cheap? 8MB of text log files is a really huge
amount of lines.
For example here I have about 9500 lines in 860MB; that would be about 92500
lines for 8MB.

> 
> On my laptop for example, there are 27 user journals, 8MiB each, where
> the last object offset is around 2MiB.  This alone burns ~162MiB in
> allocated but unused space.
> 
> We should probably have some lower level tooling for scrutinizing the
> journal files and reporting how much of the space is actually used vs.
> fallocated.
> 
> Regards,
> Vito Caputo
> _______________________________________________
> systemd‑devel mailing list
> systemd‑devel at lists.freedesktop.org 
> https://lists.freedesktop.org/mailman/listinfo/systemd‑devel