On 30.09.2014 11:15, Stefan Sperling wrote: > 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 think you have to write a tool that works agains the repos API. The Python bindings should be good enough for that. > 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? AFAIR changing largefile support does not change the APR ABI since 1.0. -- Brane
