MadDog@fool.com (Tom "Mad Dog" Yergeau) writes:
Okay, now I am really really confused.
Here's a summary of my understanding; maybe someone can point out where I'm off track.
- WAFL blocks are 4 KB
- Max # of inodes is one per 4 K block
- Each directory, even an empty one, fills at least one block
- But, up to 128 empty directories can be sqeezed into one block
1-3 are right, but not 4. An "empty" directory (they are never really empty, of course, as they have entries for "." and ".." in them) still occupies one 4 KB block in WAFL.
The *pointers* to 128 empty directories (or to anything else) can be "squeezed into one block".
So based on 3, I will run out of room before running out of inodes, but based on 4, I will run out of inodes before running out of room. (Maybe the problem is I don't understand was a dirent is?)
"dirent" = "directory entry" = "one entry in a directory". If "/foo/bar" is an empty directory, it has its own inode and its own 4 KB block with dirents for "." and ".." in it, and there is also a dirent for "bar" pointing to it and living in the directory "/foo".
There's obviously a lot of mutual incomprehension going on in this thread. I'm doing an experiment with my trusty old /vol/test which I hope should clarify what is being claimed, but I'll have to report on it tomorrow (1,000,000 mkdir's are not exactly fast...).
Slightly off topic, can anyone suggest possibly a different, non-NetApp storage/file system that will give me a lot more inodes than I can get out of a filer? (Sorry Greg, but I need the best platform to meet the needs of the application, which might or might not be NetApp, so I have to ask.) The IO demands of this application are quite low, but storage and inode requirements are high. So any solution needs to be able to store large amounts of data and provide massive quantities of inodes, but doesn't need to be as fast as a filer.
I am told that the Veritas (vxfs) filing system, unlike ufs or WAFL, can store sufficiently small directories in the inode, in the same way that WAFL does for small (<=64 bytes) regular files and symlinks.
Chris Thompson University of Cambridge Computing Service, Email: cet1@ucs.cam.ac.uk New Museums Site, Cambridge CB2 3QG, Phone: +44 1223 334715 United Kingdom.