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Solaris UFS >1TB vs. inodes

After the last episode with Solaris and ZFS, I now attempted to emulate what would have been done with ZFS, I created a meta device to stripe across the two RAID5s of the xraid (via metadb(1M) and metainit(1M)). This yielded a 5.4 TB disk, which can lateron be extended via metainit(1M) and growfs(1M).

I then proceeded to create and populate a regular UFS filesystem on the resulting disk, only to remember lateron that per default newfs(1M) enforces a ridicolous inode density on filesystems larger than one 1TB. (The 5.4 TB UFS filesystem created on Solaris provides for 5976768 inodes; my IRIX XFS filesystems that I intend to migrate contain 385056768 inodes (367GB total space) plus 2 x 1085618176 inodes (2 x 1TB total space). If I want to place all this on the single striped volume, I'll need 2556293120 inodes to just get as many as I already have; on a 5.4 TB filesystem (ie more than double the size), I'll likely need more inodes, too.)

I had to search high and lo through the interwebbing until I found this thread about the same problem. It appears that indeed the only way to create a filesystem of this size with an acceptable inode density is to compile your own 'mkfs' from OpenSolaris (for example: from here) and then run
./mkfs -F ufs /dev/md/rdsk/d1
11721015296 128 48 8192 8192 -1 1 1 16384 t 0 -1
This gave me 363413244 inodes. Still too few. Run again with
./mkfs -F ufs
/dev/md/rdsk/d1 11721015296 128 48 8192 8192 -1 1 1 8192 t 0
This gives us 721859388 inodes, or 1.8 times as many as the 367 GB XFS filesystem has. Still much less than the 1 TB XFS filesystem might had.

I don't even want to think about how long this takes to fsck, if it ever has to! So it looks like I can't have just one giant filesystem and instead will need to create many smaller filesystems. How old-fashioned! ;-/

July 26, 2006

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