On Oct 20, 2006, at 4:47 PM, Peng Gu wrote:

My question is that, when PVFS2 create a new file, does the metadata
server (MDS) know that there are enough free space on the I/O node for
this new file? In other words, does the MDS have to check the free
space on each I/O node on every file creation? Are there any potential
performance issues here?


Hi Peng,

Every file creation does go to the IO nodes to allocate the datafile handles, so the check for free space does occur. Because of this allocation on the IO servers, the performance of file creation will be slower than if it were to just go directly to the metadata server.

At some point we will probably implement batch allocation of datafile handles, and at that point creates will be able to just go to the metadata server, but as you can probably imagine, this will prevent us from doing the disk space checking that we get with the present create scheme.

-sam

Thanks,
Peng
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