Date: Fri, 14 Jun 2002 10:46:48 -0700 From: "chris" <lists@powernet.net> To: "Bill Moran" <wmoran@potentialtech.com> Cc: "Steven Goodwin" <steve@cit.gu.edu.au>, <questions@FreeBSD.ORG> Subject: Re: var optimization Message-ID: <002d01c213cb$75b0b900$a701a8c0@reno.powernet.net> References: <Pine.GSO.3.96.1020615011850.23729A-100000@kurango.cit.gu.edu.au> <000f01c213c6$844baec0$a701a8c0@reno.powernet.net> <3D0A2A49.6010407@potentialtech.com>
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You are correct, I read that TIME to SPACE... my caffeine is low again Cheers ----- Original Message ----- From: "Bill Moran" <wmoran@potentialtech.com> To: "chris" <lists@powernet.net> Cc: "Steven Goodwin" <steve@cit.gu.edu.au>; <questions@FreeBSD.ORG> Sent: Friday, June 14, 2002 10:39 AM Subject: Re: var optimization > chris wrote: > > This is usually a sign the disk is getting full. It is an automatic thing > > that happens when the disk/partition goes over a set amount(90%?) > > Check that first.... > > No, you've got it backwards ... see below. > > > ----- Original Message ----- > > From: "Steven Goodwin" <steve@cit.gu.edu.au> > > To: <questions@FreeBSD.ORG> > > Sent: Friday, June 14, 2002 8:38 AM > > Subject: var optimization > > > >>Hello FreeBSD users. I received this message immediately after (or as > >>part of) my gateway's startup. > >> > >>login: Jun 14 07:09:41 kaneda /kernel: /var: optimization changed from > >>SPACE to TIME > > Changing from SPACE to TIME indicates that the filesystem is self-tuning > itself for better performance. > Probably, what happened is that the disk got into a situation where space > was running short or it was getting very fragmented. The default > optimization is TIME (fastest writes) but when the disk gets messy, the > system will change this optimization to SPACE (slower writes, but more > organized data for faster reads). > Apparently, that condition ended (you deleted some files or over time > the SPACE optimization cleaned up the fragmentation problem) so the system > switched the optimization back to TIME (which makes for fast reads and > writes, as long as there's enough free space to support it) > fsck will print out the degree of fragmentation on a filesystem, so you > may want to check your logs to see what fsck has been saying at bootup > time. If you check your system logs, I'm sure you'll see that at some > point in the past, the system switched from TIME to SPACE, and it's now > switching back. > > >>This may or may not be the place to ask this question, but could anyone > >>satisfy my curiosity and explain (or point me to some documentation that > >>explains) which process or part of the kernel makes this decision and what > >>are the reasons/criteria for the change. > > The tunefs man page has a bit in it about this, as well as the newfs man > page. > As to which part of the kernel, it's either the ufs or the ffs drivers. I > don't know the exact methodology/reasons for the change, the above is a > high-level look. There is a doc in /usr/share/doc called diskperf that will > probably have some more details on how/why this occurs. > > -- > Bill Moran > Potential Technology > http://www.potentialtech.com > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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