Hi Artem!
Artem Trunov wrote:
> Hi, all
>
> How does xrootd interact with underlying file system? Are there
> tunable parameters? Like blocksize for i/o requests?
I guess that those tweaks are to be found in the OS. Afaik in xrootd you
can only tune the size of the subchunks in which a bigger block is to be
split, but I believe that it's not used in your use cases.
> When a client
> sets readahead parameter, is it effectively a single disk read
> operation? What about writing?
In single tcp stream mode the client generally does not split blocks, so
the server gets a ingle request, when you enable the multiple tcp sterams
instead nearly all the blocks are splitted in various subchunks, so it's not.
For writes xrdcp/XrdClient applies the same algorithm.
>
> Also xrdcp - the same questions - is it possible to tune disk i/o?
>
When writing to the local disk? No, it writes what the server sends in
4M/8M blocks, trying to make them sequential. The only parameters are those
in the OS filesystem config.
Fabrizio
> cheers
> Artem.
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