Date: Fri, 21 Dec 2007 20:55:22 -0300 From: "Alexandre Biancalana" <biancalana@gmail.com> To: "Alfred Perlstein" <alfred@freebsd.org> Cc: freebsd-performance@freebsd.org Subject: Re: Bad performance when accessing a lot of small files Message-ID: <8e10486b0712211555n3efe8729qff14387be128cf10@mail.gmail.com> In-Reply-To: <20071221212808.GE16982@elvis.mu.org> References: <8e10486b0712191109n3d21b02cyf5183ee0cd01d8ce@mail.gmail.com> <20071221201625.GZ16982@elvis.mu.org> <8e10486b0712211249v4c5571ddud21b277f686992b2@mail.gmail.com> <20071221212808.GE16982@elvis.mu.org>
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On 12/21/07, Alfred Perlstein <alfred@freebsd.org> wrote: > * Alexandre Biancalana <biancalana@gmail.com> [071221 12:48] wrote: > > On 12/21/07, Alfred Perlstein <alfred@freebsd.org> wrote: > > > > Hi Alfred ! > > > > > > > > There is a lot of very good tuning advice in this thread, however > > > one thing to note is that having ~1 million files in a directory > > > is not a very good thing to do on just about any filesystem. > > > > I think I was not clear, I will try explain better. > > > > This Backup Server has a /backup zfs filesystem of 4TB. > > > > Each host that do backups to this server has a /backup/<hostname> and > > /backup/<hostname>/YYYYMMDD zfs filesystems, the last contains the > > backups for some day of that server. > > > > My problem is with some hosts that have in your directory structure a > > lot of small files, independent of the hierarchy. > > Can you not tar these files together? This is what I'm trying to do.... > > > > One trick that a lot of people do is hashing the directories themselves > > > so that you use some kind of computation to break this huge dir into > > > multiple smaller dirs. > > > > I have the two cases, when you have a lot of files inside on directory > > without any directory organization/distribution but I also have > > problems with hosts that have files organized in a hierarchy like > > YYYY/MM/DD/<files> having no more that 200 files in the day directory > > level, but almost one million of files in total. > > > > Just for info, I made the previous suggested tuning (raise dirhash, > > maxvnodes) but this improve nothing. > > > > Thanks for your hint! > > What application are you scanning these files with? I know I had > issues with rsync in particular where I had to have it rsync > smaller pieces of a collection for it to work nicely instead of > going for the whole heirarchy. tar I run tar in the /backup/<hostname>/YYYYMMDD writing to LTO3 tape drive, the problem is that when origin directory contains a lot of small files the process is *much* more slow.... this is my question since the thread start.
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