Claus Guttesen writes:
> > > I have many small - mostly jpg - files where the original file is
> > > approx. 1 MB and the thumbnail generated is approx. 4 KB. The files
> > > are currently on vxfs. I have copied all files from one partition onto
> > > a zfs-ditto. The vxfs-partition occupies 401 GB and zfs 449 GB. Most
> > > files uploaded are in jpg and all thumbnails are always jpg.
> >
> > Is there a problem?
>
> Not by the diskusage itself. But if zfs takes up more space than vxfs
> (12 %) 80 TB will become 89 TB instead (our current storage) and add
> cost.
>
> > Also, how are you measuring this (what commands)?
>
> I did a 'df -h'.
>
> > > Will a different volblocksize (during creation of the partition) make
> > > better use of the available diskspace? Will (meta)data require less
> > > space if compression is enabled?
> >
> > volblocksize won't have any affect on file systems, it is for zvols.
> > Perhaps you mean recordsize? But recall that recordsize is the maximum
> > limit,
> > not the actual limit, which is decided dynamically.
> >
> > > I read
> > > http://www.opensolaris.org/jive/thread.jspa?threadID=37673&tstart=105
> > > which is very similar to my case except for the file type. But no
> > > clear pointers otherwise.
> >
> > A good start would be to find the distribution of file sizes.
>
> The files are approx. 1 MB with an thumbnail of approx. 4 KB.
>
So the 1 MB files are stored as ~8 x 128K recordsize.
Because of
5003563 use smaller "tail block" for last block of object
The last block of you file is partially used. It will depend
on your filesize distribution by without that info we can
only guess that we're wasting an avg of 64K per file. Or 6%.
If your distribution is such that most files are slightly
more than 1M, then we'd have 12% overhead from this effect.
So using 16K/32K recordsize would quite possibly help as
files would be stored using ~ 64 x 16K blocks with an
overhead of < 1-2% (0.5 blocks wasted every 64).
-r
> --
> regards
> Claus
>
> When lenity and cruelty play for a kingdom,
> the gentlest gamester is the soonest winner.
>
> Shakespeare
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