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Re: Inode/Blocksize questions

On Tue, Apr 30, 2002 at 12:30:17AM +0200, Michael Renner wrote:
> On Mon, 29 Apr 2002, Theodore Ts'o wrote:
> > For files as small as single mail messages (i.e., averaging about
> > 8-9k, rarely as larger than half a meg except for Windows virus
> > messages), the performance gain for using a 4k blocksize is probably
> > not all that great.  So you might want to use a 1k blocksize just to
> > minimize the overhead.
> Ok.
> Here are some completely unreliable (only one run) bonnie++ benchmark
> results:

By default, Bonnie++ does its tests using 200 megabyte files.  I
explicitly qualified my statement by saying that if you're just going
to be writing small files (i.e., the vast majority of them less than
16k, as you might expect using the Maildir format, or a news spool ---
where very message gets its own file), you're not going to see that
much performance difference between 4k and 1k blocksizes.

(Personally I think the Maildir format is completely silly and
optimizes for the wrong thing, but then again, I disagree with many
other things devised by Dan Bernstein.)

> > > With default options, the number of inodes mke2fs creates is 1 per 8kB of
> > > disk space.
> >
> > In other words, mke2fs creates enough inodes for the case where the
> > average size of a file on the filesystem is larger than 8k.  If you
> > think you will be receiving a large number of small messages, it might
> > be wise to set the bytes-per-inode setting (via the -i option of
> > mke2fs) to 4096.  This will mean the filesystem will have enough
> > inodes even if the average file size is as small as 4k.
> Well, the default seems fine to me (7553013 inodes on a ~53 gig
> partition). Our old mailserver which only has a 15 gig maildir storage
> uses only ~500000 inodes.

Well, it all depends on what you think the average size of a mail
message is.  These days, it's a lot higher than it used to be, because
I keep getting so many Windows virii being mailed to me....  :-/

						- Ted

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