[Pvfs2-developers] Changing the number of I/O servers

[Kevin Harms]

Christina,

   you are using MPICH2 and the ad_pvfs2 romio module?

kevin

On Jul 14, 2009, at 9:12 AM, Christina Patrick wrote:

> Hi Everybody,
>
> I want to use MPI hints to create a striped file across a subset of
> the pvfs2 servers. For that I use, the hints "striping_unit" and
> "striping_factor". I have a set of three I/O servers. However, I want
> to create the file only on one I/O server. I specified "striping_unit"
> = 65536 and "striping_factor" = 1. However, after the file is created,
> I get the following results:
>
> pvfs2-viewdist -f /home/mdl/patrick/pvfs2/oneserver
> dist_name = simple_stripe
> dist_params:
> strip_size:65536
>
> Metadataserver: tcp://aum14:7000
> Number of datafiles/servers = 3
> Datafile 0 - tcp://aum15:7000, handle: 9223372036854775298
> (7ffffffffffffe02.bstream)
> Datafile 1 - tcp://aum13:7000, handle: 4611686018427387650
> (3fffffffffffff02.bstream)
> Datafile 2 - tcp://aum14:7000, handle: 4611686018427387905
> (4000000000000001.bstream)
>
> Am I missing something? I wanted to use this hint, so that I don't
> have to reconfigure the servers everytime, I want to change the number
> of I/O servers.
> Could somebody please help me?
>
> Thanks and Regards,
> Christina.
>
> PS: The extract from my program which does this:
>     79   MPI_Info_create(&file_info);
>     80
>     81   if(argc > 1) {
>     82     stripe_unit = atoi(argv[1]);
>     83     sprintf(stripe_unit_str, "%d", stripe_unit);
>     84     MPI_Info_set(file_info, "striping_unit", stripe_unit_str);
>     85   }
>     86
>     87   if(argc > 2) {
>     88     stripe_factor = atoi(argv[2]);
>     89     sprintf(stripe_factor_str, "%d", stripe_factor);
>     90     MPI_Info_set(file_info, "striping_factor",  
> stripe_factor_str);
>     91   }
>     92
>     93   MPI_File_open(MPI_COMM_WORLD, fname, MPI_MODE_CREATE |
> MPI_MODE_WRONLY, file_info, &fhandle);
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