Juha Saarinen wrote:
>
> On Sun, 6 May 2001, GCS wrote:
>
> > This means, if you create millions of very small files,
> > and after you delete them, you see your disk storage size shrink.
>
> If that's correct, XFS would be less than ideal for e.g. a Squid or a news
> volume.
It is correct, but it doesn't necessarily follow that it's a poor choice
for a news server or other application that has a large number of files.
It's NOT that every created inode wastes space. If you have some
application that, on average, uses 1 million inodes, and sometimes
spikes to 1.1 million inodes, then you might sometimes have 100,000
unused, but still allocated, inodes on the system.
In other words, the "high water mark" of allocated inodes is never
reduced.
But that's not so bad - create a fresh ext2 system, and you start off
with allocated, but 100% unused inodes right from the start. And if you
didn't create it with _enough_ inodes, then your app will fail when it
runs out. So you make the ext2 filesystem with, maybe, 1.5x what you
anticipate. Which seems like a bigger waste...
So with XFS, you only waste space if you dramatically change the inode
usage downward. If you use a filesystem for a squid cache, then delete
all those files and make one big vidcap file, then yes, you'd be wasting
space. But that sort of scenario isn't too likely.
-Eric
--
Eric Sandeen XFS for Linux http://oss.sgi.com/projects/xfs
sandeen@xxxxxxx SGI, Inc.
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