On Feb 2, 2007, at 4:15 PM, Sam Lang wrote:
On Feb 2, 2007, at 3:28 PM, Steve wrote:
Hi,
Is there any rough rule of thumb guide for the size of the
metadata for the
size of the store ?
Hi Steve,
The size of the metadata as a percent of the size of the storage
space depends on the sizes of the files. I'm doing a back of the
envelope calculation, but I think that in general, each file takes
up somewhere around 650 bytes to store its metadata, while
directories are a little less (maybe 500 bytes). Remember though
that the metadata size changes for different configurations (more
servers, etc.). There's also overhead related to the storage space
itself, which is about (100K * numservers). If you know how many
files/directories you have in your volume, you should be able to
get a rough estimate of your metadata size using those numbers above.
I should clarify though, that the filesystem size (capacity and
available) reported by df for PVFS volumes is just the sum of the
sizes on each of the IO servers (capacity is actually the min of all
servers * numservers). This means that what df reports in terms of
usage can be inaccurate if the PVFS storage on the IO nodes is shared
with other files.
-sam
-sam
Steve
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