Date: Fri, 10 May 1996 15:17:50 -0400 From: Parag Chhibber <pchhibbe@attila.stevens-tech.edu> To: freebsd-hackers@freebsd.org Subject: Allocation Unit and File System in General Message-ID: <2.2.32.19960510191750.006baf38@attila.stevens-tech.edu>
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Hi. I was wondering what type of file system is used by FreeBSD, and more importantly, what are the size of the allocation units? In DOS (which sucks) the file system supports names of 8+3 with allocation unit sizes differing depending on the partition size as follows: Hard Disk Allocation Unit Minimum Size 0 MB 512 bytes 32 MB 1024 bytes (1 KB) 64 MB 2048 bytes (2 KB) 128 MB 4096 bytes (4 KB) 256 MB 8192 bytes (8 KB) 512 MB 16384 bytes (16 KB) 1024 MB 32768 bytes (32 KB) 2048 MB 65536 bytes (64 KB) and so on... This means that if you have a 1.2 GB drive, in DOS, if you leave it as 1 partition, your allocation unit is 32 KB. If you split the drive into 3 partitions, your allocation untis is 8 KB. Basically your allocation unit is the minimum multiple that your actual file size must take up. (For example, with 32 KB allocation units, files less then 32 KB take up 32 KB, and files greater then that take up multiples of 32 KB rounding up.) My question is how are allocation units handled in FreeBSD, because with disk striping and such, disk sizes can become pretty big. Sorry for the length of this question, but I got carried away... Thanks in advance for all your time and effort. Parag Chhibber ============================================================= Stevens Institute of Technology Home Address: S-247, Technology Hall #608 15 Powderhorn Drive Castle Point on the Hudson Kinnelon, New Jersey 07405-2936 Hoboken, New Jersey, 07030 (201) 492 - 2698 (201) 216 - 3611 E-mail: mailto:parag@gsi.gsini.net WWW: http://gsi.gsini.net/~parag/ http://attila.stevens-tech.edu/~pchhibbe/ =============================================================================
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