Date: Tue, 29 May 2012 18:00:20 +1000 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Bruce Evans <brde@optusnet.com.au> Cc: freebsd-fs@FreeBSD.org, Doug Barton <dougb@FreeBSD.org> Subject: Re: Millions of small files: best filesystem / best options Message-ID: <20120529175504.K1291@besplex.bde.org> In-Reply-To: <20120529161802.N975@besplex.bde.org> References: <1490568508.7110.1338224468089.JavaMail.root@zimbra.interconnessioni.it> <4FC457F7.9000800@FreeBSD.org> <20120529161802.N975@besplex.bde.org>
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On Tue, 29 May 2012, Bruce Evans wrote: > ... > - it is easy to fix ffs to support a minimum block size of 512 (by > reducing its gratuitous limit of MINBSIZE and fixing the few things > that break: > On Mon, 28 May 2012, Doug Barton wrote: >> The good news is that it's a big improvement (I've done similar >> stuff in the past). You'll also want to tweak the -i (inode) value to >> insure that you have sufficient inodes for the number of files you plan >> to store. The default is not likely to be adequate for your needs. > > Big is relative. 4K-blocks with 200-byte files gives a wastage factor > of 20. Metadata alone will be 256 bytes for the inode alone with ffs2. > Only 128 bytes with ffs1. Only 32 bytes with msdosfs. Oops, only a wastage factor of 2.5 with the 512-byte fragments that are normally used with 4K-blocks by ffs. 512-byte blocks with ffs only give a small reduction in metadata size and better block allocation. Bruce
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