On 2007-Jun-27 14:11:19 +0400, Nguyen Tam Chinh <[EMAIL PROTECTED]> wrote: > We're going to build a server with some 1Tb of over 500 million small > files with size from 0,5k to 4k. I'm wonder if the ufs2 can handle > this kind of system well.
Short answer: No. Longer answer: FreeBSD and UFS2 have been tweaked to support large numbers of files in larger filesystems and there are no hard limits that you will exceed by having 500,000,000 files in a >1TB FS. However, you will not be able to fsck the FS on an i386 system and will need a lot of RAM+SWAP on amd64 or SPARC64. fsck will also take a _long_ time (hours) to run. Depending on how the files are organised, you may run into severe performance problems with directory searching. > From newfs(8) the min block size is 4k. This > is not optimal in our case, a 1k or 0,5k block is more effective IMHO. > I'd be happy if anyone can suggest what does fragment (block/8) in the > ufs2 mean and how this parameter works. I suggest you read /usr/share/doc/smm/05.fastfs/paper.ascii.gz Whilst this paper discusses UFS1, the basics remain the same. I have tried using a 4K/0.5K UFS1 filesystem in the past and found the performance was very poor. UFS2 was based on 16K/2K and I would expect it to perform even worse with 4K/0.5K. I would suggest you try 8K/1K. BTW, in sizing your system, you will need to allow for both the last space when the file sizes are rounded up to a multiple of the fragment size, as well as the inode size (256 bytes). If you have 1TB of data, it's likely that you will have another 0.5-1TB of overheads. Overall, I suggest you look at an alternative way to store the data. -- Peter Jeremy
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