On 20/07/15 15:31, Anne Mulhern wrote: > ----- Original Message ----- >> From: "Colin Guthrie" <gm...@colin.guthr.ie> >> To: systemd-devel@lists.freedesktop.org >> Sent: Monday, July 20, 2015 5:38:38 AM >> Subject: Re: [systemd-devel] Confusing journal information - journal size >> >> David Sommerseth wrote on 17/07/15 14:28: >>> On 17/07/15 13:31, Mantas Mikulėnas wrote: >>>> On Fri, Jul 17, 2015 at 2:13 PM, David Sommerseth <dav...@redhat.com >>>> <mailto:dav...@redhat.com>> wrote: >>>> >>>> >>>> Hi, >>>> >>>> I'm looking through some journals now, and even though I've seen it a >>>> few times I haven't thought about it until now. >>>> >>>> systemd-journal[1151]: Runtime journal is using 8.0M (max allowed >>>> 4.0G, trying to leave 4.0G free of 63.7G available → >>>> current limit 4.0G). >>>> >>>> Could this line be cleaned up so you don't have to look up a man page >>>> to >>>> try to figure out what this really means? Here's my uneducated guess >>>> and confusion of this line: >>>> >>>> * Runtime journal is using 8.0M >>>> - Okay, so currently the journal uses 8MB of disk-space. No >>>> problem. >>>> >>>> * max allowed 4.0G >>>> - Okay, so the journal should not grow beyond 4GB, makes sense. No >>>> problem. >>>> >>>> * trying to leave 4.0G free of 63.7G available >>>> - Uhm, what!? So it will grow until there is 4GB left on the >>>> filesystem? Not so okay. >>>> >>>> >>>> It chooses the /smallest/ limit, not largest. (Common sense...) For >>>> example, if you had only 5 GB space available, the journal would not >>>> grow beyond 1 GB. >>>> >>>> >>>> * current limit 4.0G >>>> - Ehh ... okay ... so make up your mind, please! So will the >>>> journal grow until 4GB or 59.7GB. >>>> >>>> >>>> This *is* it making up its mind: "min(limit 1, limit 2) → resulting limit" >>>> >>>> But then I looked into /var/log/journal ... >>>> >>>> # du --si -s /var/log/journal/ >>>> 4.3G /var/log/journal/ >>>> >>>> I do see that both system,journal and user-UID.journal are both 8.4MB, >>>> and from that I can guess what the log entry tried to tell me with >>>> "Runtime journal" ... but how is /that/ information useful for me, >>>> from >>>> a sys-admin point of view? >>>> >>>> >>>> "Runtime" here means /run, as opposed to persistent in /var. They have >>>> separately configurable limits, since /run is in RAM and /var is usually >>>> on disk. (Though, I'm not entirely sure what purpose the runtime journal >>>> even serves, when /var is available.) >>> >>> Fair enough. But you are missing my point. >>> >>> How this information is presented do require some detail knowledge of >>> the journal. Don't think like a developer who have poked at the journal >>> code. Think like a sys-admin who looks through the logs looking for >>> issues. Then you want to have the answer straight in your face, not >>> needing to go elsewhere to read about these things. In fact most admins >>> will probably have forgotten what they were going to look for when they >>> move their eyes of the log data. >>> >>> If it is considered important information, fine. But present it in a >>> far more understandable way for those who just uses the journal. Right >>> now, I'm not surprised if most sys-admins read that line as useless >>> gibberish - "Yeah, yeah, journal will waste some space on my drive". >> >> Yeah, I can't disagree with David. Not sure how best to tidy it up, but >> some rework would definitely be nice. >> >> Col >> > > After seeing the explanation, the best complete and correct (AFAICT) > formulation I could come up with was, > > "Runtime journal is using 8.0M (max allowed = min(4.0G, S s.t. total > memory(63.7 G) - S = 4.0 G (59.7 G), available memory (16.2 G)) = 4.0G)" > > which is compelled to use math speak for clarity and succinctness. > > Dunno how happy most sys-admins would be with that. > > - mulhern
But is all that information really needed? If I try to see this from a sys-admin point of view there are two numbers which are important to me: 1) Current state 2) Final journal limit size. From how I see it, how the journal code ends up with a certain number is only useful when you're developing/debugging the journal. Remember: Less is more. -- kind regards, David Sommerseth _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
