On Mon, Sep 29, 2014 at 07:18:05PM +0200, Stefan Fuhrmann wrote: > On Sun, Sep 28, 2014 at 11:17 PM, Stefan Sperling <s...@apache.org> wrote: > > > On Sun, Sep 28, 2014 at 05:56:01PM -0000, stef...@apache.org wrote: > > > Author: stefan2 > > > Date: Sun Sep 28 17:56:01 2014 > > > New Revision: 1628093 > > > > > > URL: http://svn.apache.org/r1628093 > > > Log: > > > Support FSFS format 7 commits in load balanced mixed-architecture > > clusters. > > > > > > At least theoretically, machines with different endianess or off_t sizes > > > might access the same repository on e.g. an iSCSI SAN. Then the machine > > > performing a commit may have a different architecture from the one > > building > > > up the transaction. To allow that, even the intermediate (proto-) index > > > format within those transactions must be platform-independent. > > > > Hi Stefan, > > > > If you describe in some more detail how to set it up I can test this > > scenario for you on OpenBSD with sparc64 (64bit big-endian), amd64 > > (64bit little endian), macppc (32bit big-endian) and i386 (32bit little > > endian) machines. > > > > Thanks for the offer. So, this is the issue that I addressed > with the above patch: > > At the FS API level, transactions can be opened (and implicitly > closed again) many times before being committed. If these > operations are performed from different machines accessing > the same repository, they might not agree upon C struct size, > layout or interpretation. So, for pure API consistency alone, > all data within a txn needs to be portable / architecture independent. > > I may be wrong but I vaguely remember that the HTTP client > sends the "commit" operation over a separate connection that > the one it used to build up the txn. If there is a load balancer > in front of the actual servers, that commit may get served by > a different machine. > > Testing the general scenario is simpler, though. Have one machine > build up a transaction which touches a few of nodes (such that > different record sizes would result in missing / misaligned data). > Then e.g. copy the repo to a different machine and let that one > do the commit. The result must then pass 'svnadmin verify'. > > The critical combinations are little / big endian and 32 bit vs. > 64 bit file offsets (not the same thing as 32 / 64 bit in general). > So, 64 bit big endian vs. 32 bit little endian with 32 bit off_t > would probably cover it. Tests with both machines in both > roles (txn creation and txn commit). > > -- Stefan^2.
How do you open a transaction and postpone the commit? Using some custom code written against the FS API? Or can some tool such as svnmucc already do this? I presume you rely on apr_off_t, not off_t, right? I.e. it's enough to recompile APR and SVN with or without large file support to switch between 32bit and 64bit apr_off_t?
