Subject: Re: Aliases: Are alternate filesystems worth trying?
From: Matthew Geier (matthew@arts.usyd.edu.au)
Date: Fri Jun 08 2001 - 19:26:52 EDT
Richard Goldman wrote:
>
> Well, gotta retract a few things here, sorry folks:
>
> If an XFS volume is created as I've suggested (in this case on a 36GB raid 5 md), the "df -i" command reports that I have 4,480,192 inodes to play with -- certainly less than the 16,777,216 that can be encoded in an alias.
>
> However, after stress-testing and adding about 100,000 new files and directories to the raid, I have inode numbers higher than 16,777,216, which is not safe. Matthew Geier, I believe, had mentioned that XFS inodes may "encode a disk address..." and not be members of a fixed pool.
While I wouldn't say for sure with out reading the XFS 'whitepapers', I
understand from the XFS list, that Inodes are not fixed in number. XFS
allocates more inode space as required.
All df -i will do is tell you what is currently allocated (I think). If
you ever ran out of inodes the file system would allocate more.
The inode numbers on XFS are 64bit and encode the address of either the
inode block or the first extent of the file.
Even with the new mtab scheme, with 64 bit Inodes on XFS , there is
going to be a massive loss of information when 34 bits of the inode
number are thrown away.
And you can't configure an XFS file system with a smaller than 2^30
inodes to prevent the clash from happening.
Presumably its impossible to have more than 2^30 files on a HFS disk
over the entire lifetime of the filesystem. Seems like a bit of a
serious long term restriction?.
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