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Disk format change for trunk's FSFS version 7

From: Philip Martin <philip.martin_at_wandisco.com>
Date: Mon, 03 Mar 2014 13:03:49 +0000

Stefan Fuhrmann <stefan.fuhrmann_at_wandisco.com> writes:

> On Sun, Mar 2, 2014 at 2:54 AM, Philip Martin <philip.martin_at_wandisco.com>wrote:
>
>> There is a problem with the FNV1a checksums in format 7: the on-disk
>> representation for big-endian systems, like SPARC, is different from
>> that of little-endian systems, like x86. Both systems calculate the
>> same checksum value, however the checksum code calls htonl() before
>> returning the value to the caller. On SPARC this has no effect and on
>> x86 it reverses the byte order, changing the value. If we were to write
>> the resulting memory directly to disk as a block of data this would be
>> good because the disk representations would be the same, but that is not
>> what happens. The value is passed to encode_uint() which uses arithmetic
>> to write out a representation of the bytes. Since the htonl() call
>> changes the x86 value this means the disk representation changes.

> Committed with a few addition as r1573371 and r1573375.

This changes the on-disk representation for the unreleased FSFS format 7
on little-endian systems, that's probably most systems. Anyone with
repositories in this format needs to dump/load.

-- 
Philip Martin | Subversion Committer
WANdisco // *Non-Stop Data*
Received on 2014-03-03 14:04:31 CET

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