Date: Thu, 18 Oct 2001 18:40:24 -0400 From: Garance A Drosihn <drosih@rpi.edu> To: "David W. Chapman Jr." <dwcjr@inethouston.net>, "Chad R. Larson" <chad@DCFinc.com> Cc: "Rasputin" <rasputin@submonkey.net>, "Doug Poland" <doug@polands.org>, <stable@FreeBSD.ORG> Subject: Re: dirpref gives massive performance boost Message-ID: <p05101001b7f4edad0a69@[128.113.24.47]> In-Reply-To: <01c701c157fa$d8449ba0$fe0c4042@inethouston.net> References: <20010928141246.A15515@xor.obsecurity.org> <20011002212002.4034283f.steveo@eircom.net> <20011002214353.A653@student.uu.se> <20011018083713.A20403@polands.org> <20011018144850.A1943@shikima.mine.nu> <20011018105736.A43973@leviathan.inethouston.net> <p05101005b7f4bb89498e@[128.113.24.47]> <01c101c157f9$87868da0$fe0c4042@inethouston.net> <20011018103048.B545@freeway.dcfinc.com> <01c701c157fa$d8449ba0$fe0c4042@inethouston.net>
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At 12:32 PM -0500 10/18/01, David W. Chapman Jr. wrote: >Well yes, but I would like to avoid all of this if it is already >using dirpref. I currently don't have enough drive space to fully >backup my 24gig stripe set. Assuming you are up-to-the-minute with 4.4-stable, then your system is already "using" dirpref. "Using" in the sense that the system will do a better job of laying out information on the disk for any new directories which are created. What you are basically asking is, "How do I find out if every directory on this partition was written after I installed the update which made the system smarter about laying out information on the hard disk?". The answer is "There is no tool which exists which could tell you what you want to know". I completely understand why you want to know, but it is still true that there is no program which will look at a given file system and figure out what you want to know. As I was in a somewhat similar situation to yours, let me tell you what I did. I did a 'cd' into one of the larger partitions that I mount. I did a 'du -s *' to figure out which of the sub-directories were the largest (the root-level of the partition had nothing but about 10 directories in it). I then picked the largest directories, backed them up into a gzip'ed tar archive, removed the directories, did a few 'sync's for good measure (to make sure softupdates had written out the information for all that disk space which had been freed). I then restored the directories from my tar-archive. This meant that a significantly higher percentage of the files on that partition were written out using the newer, smarter layout. So, instead of being 2% dirpref, it was maybe 95% dirpref. Now it would have been even better to back up all of it, 'newfs', and restore all of it, but I didn't have the disk space for some of my larger partitions. And it certainly DID improve performance. For this to make a big difference, though, you need to be able to remove a pretty significant percentage of the information on your partition. -- Garance Alistair Drosehn = gad@eclipse.acs.rpi.edu Senior Systems Programmer or gad@freebsd.org Rensselaer Polytechnic Institute or drosih@rpi.edu To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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