Date: Tue, 09 Jan 2007 12:49:29 -0600 From: Guy Helmer <ghelmer@palisadesys.com> To: freebsd-stable@freebsd.org, ghelmer@palisadesys.com Subject: Re: 6.x loosing record of free space after filesystem fills? Message-ID: <45A3E3B9.4030205@palisadesys.com> In-Reply-To: <200701091737.l09HbGSZ026335@lurza.secnetix.de> References: <200701091737.l09HbGSZ026335@lurza.secnetix.de>
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Oliver Fromme wrote: > Guy Helmer wrote: > > I think we've finally found the cause of the problem - it wasn't just > > occurring after heavy use, but was visible right after filesystem > > creation! We regularly built new filesystems with "newfs -U -O 1 -b > > 65536 -f 8192" > > Why are you using those blocksize and fragsize settings? > (If you store large files, then you should at least also > decrease the inode density, using the -i option.) > These settings were chosen to optimize I/O throughput for Postgresql on the theory that a 64KB block size would maximize disk throughput in the general case (especially for a RAID 10 system) and an 8K frag size would match Postgresql's page size. I wasn't aware of any known regressions in 6.x regarding large filesystem block sizes... > Some time ago, Joe Greco wrote: > > > the one unusual thing about the configuration is that the filesystem > > > we are attempting to build on is a 136GB ccd across 4 scsi disks with > > > the fsize=8192 and the bsize=65536 (it is mainly to be used for large > > > data log files): > > > > FreeBSD doesn't support fsize/bsize so large. There are ongoing issues > > within the filesystem code and VM code that will cause such filesystems > > to break under heavy load. Matt Dillon also talked about this being less- > > than-optimal for the VM system from some technical points of view. > > It has been a while, and I'm not sure if there are still > problems with those non-standard fsize/bsize settings, but > I would definitely try to avoid them for production use. > > Best regards > Oliver > > Thanks, Guy
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