Ed,
At 10:39 AM -0700 2/21/08, Ed Hartnett wrote:
Elena Pourmal <epourmal@xxxxxxxxxxxx> writes:
Ed,
Here is some documentation on Fletcher32
http://www.hdfgroup.uiuc.edu/RFC/HDF5/ARCHIVE/H5checksum/
This document describes the final design and implementation
http://www.hdfgroup.uiuc.edu/RFC/HDF5/ARCHIVE/H5checksum/EDC_spec.htm
Checksum is ON by default, i.e read operation will fail, but there
is an API that allows you to disable checksum and get data back.
Elena
OK, thanks!
Is the following correct:
Turning on the fletcher32 checksum filter causes a 4 byte-checksum to
be written with each chunk.
Yes, this is correct.
(What happens to contiguous data?)
Any filter in HDF5 requires chunking storage; one cannot (at least
now) apply checksum to contiguous data.
When reading data with fletcher32 checksum enabled, any corruption of
the chunk will cause the read operation to fail.
There is a significant performance penalty when reading checksummed
data.
Is this all correct?
Yes, it is correct, but I believe "significant " will vary from
system to system.
Elena
Thanks!
Ed
--
Ed Hartnett -- ed@xxxxxxxxxxxxxxxx
--
------------------------------------------------------------
Elena Pourmal
The HDF Group
1901 So First ST.
Suite C-2
Champaign, IL 61820
epourmal@xxxxxxxxxxxx
(217)333-0238 (office)
(217)333-9049 (fax)
------------------------------------------------------------
