is hammer for us

Mag Gam magawake at
Tue Aug 11 20:56:30 PDT 2009

The I/O bottleneck is coming from the disk subsystem and network. I
was wondering if HAMMER can do parallel filesystem implementation
similar to GPFS or Lustre.

Also, the reads/writes are random access there is very little
sequential streaming, but the files are large.Each file is around 30GB

On Tue, Aug 11, 2009 at 11:42 PM, Matthew
Dillon<dillon at> wrote:
> :I am a student doing fluid dynamics research. We generate a lot of
> :data (close to 2TB a day). We are having scalability problems with
> :NFS. We have 2 Linux servers with 64GB of RAM, and they are serving
> :the files.
> :
> :We are constantly running into I/O bottle neck problems. Would hammer
> :fix the scalability problems?
> :
> :TIA
>    If you are hitting an I/O bottleneck you need to determine where the
>    bottleneck is.  Is it in the actual accesses to the disk subsystem?
>    Are the disks seeking randomly or accessing data linearly?  Is the
>    transfer rate acceptable?  Is it the network?  Is it the NFS
>    implementation?  Is it the underlying filesystem on the server?  Are
>    there parallelism issues?
>    You need to find the answer to those questions before you can determine
>    a solution.
>    Serving large files typically does not create a filesystem bottleneck.
>    i.e. any filesystem, even something like ZFS, should still be able
>    to serve large linear files at the platter rate.  Having a lot of ram
>    only helps if there is some locality of reference in the data set.
>    i.e. if the data set is much larger then available memory but there
>    is no locality of reference and the disk drives are hitting their seek
>    limits, no amount of ram will solve the problem.
>    (DragonFly's 64 bit support isn't reliable yet, so DragonFly can't
>    access that amount of ram right now anyhow).
>                                        -Matt
>                                        Matthew Dillon
>                                        <dillon at>

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