raj@pollux.ncgia.ucsb.edu (Richard A Johnson) (08/14/90)
If you create a symlink to a file where the reference name in the symlink is less than 48 characters long, I'm told (by people in Austin) that the info. is stored in the inode. However, if it's more than 48 characters long the system allocates the smallest "block size" chunk of the filesystem for that file. This "smallest block size" is 4K! This means that if you are creating a lot of symlinks (such as symlinking the X11 distribution [the one from MIT, not the smaller copy from IBM] for compilation of different machine types), you can eat up disk space REAL FAST! This is a problem! Austin says this value can't be changed, but maybe that's because there isn't an easy user interface which allows one to change it. Has anyone found ANY WAY to change the block size on and AIX filesystem? I'm not opposed to using adb on the raw device. I've done such things before on other versions of Unix. ANY info. AT ALL would be VERY MUCH APPRECIATED! ----------------------------------------------------------------------------- Richard A. Johnson raj@topdog.ucsb.edu (Internet) NCGIA Computing Resources Manager ucbvax!ucivax!raj (UUCP) U. C. Santa Barbara raj@pollux.ncgia.ucsb.edu (via Nameservers)
jonathan@speedy.cs.pitt.edu (Jonathan Eunice) (08/21/90)
Richard Johnson (raj@pollux.ncgia.ucsb.edu) writes: | If you create a symlink to a file where the reference name in the symlink | is less than 48 characters long, I'm told (by people in Austin) that the info. | is stored in the inode. However, if it's more than 48 characters long the | system allocates the smallest "block size" chunk of the filesystem for that | file. This "smallest block size" is 4K! This means that if you are creating | a lot of symlinks (such as symlinking the X11 distribution [the one from MIT, | not the smaller copy from IBM] for compilation of different machine types), | you can eat up disk space REAL FAST! This is a problem! It's my understanding that the JFS block size is fixed at 4 KB, and that disk block fragmentation (a la BSD UFS) is not available. So, tiny files and sym links (in your situation, really just special kinds of tiny files) devour disk space. This is one (significant) reason those ~120 MB disks are de-emphasized -- too much space wastage to make them relevant/useful. Perhaps in a future version of AIX JFS will implement fragmented blocks, or IBM will offer the BSD FFS/UFS as an option. I'm afraid that the current solution appears to be buying more disk.