Re: [Bacula-users] Quantum Scalar i500 slow write speed

[Henry Y. <he...@Ae...>]

On Thu, Aug 05, 2010 at 10:09:06AM -0400, John Drescher wrote:
> On Thu, Aug 5, 2010 at 8:57 AM, Henry Yen <he...@ae...> wrote:

> > On (at least) Linux, /dev/random will quickly block - use /dev/urandom instead.
> 
> Since these tend to be slow I would just create a large file from one of these.

Well, for this case you shouldn't simply pick one or the other.

Again, on Linux, you generally can't use /dev/random at all -- it will
block after reading just a few dozen bytes.  /dev/urandom won't block,
but your suggestion of creating a large file from it is very sensible.
/dev/urandom seems to measure about 3MB/sec or thereabouts, so creating
a large "uncompressible" file could be done sort of like:

   dd if=/dev/urandom of=tempchunk count=1048576
   cat tempchunk tempchunk tempchunk tempchunk tempchunk tempchunk > bigfile

-- 
Henry Yen                                       Aegis Information Systems, Inc.
Senior Systems Programmer                       Hicksville, New York