innodb_log_block_size=4096 is not supported

This has to be verified. xtrabackup.c does support setting innodb_log_block_size and seems to use it at prepare. We need a test case, which I don't have time to construct.

Support isn't complete. log_block_size is set inside innodb_init_param, while error is thrown from inside xtrabackup_init_temp_log, which is called before innodb_init_param.

120614 12:55:59 innobackupex: Starting ibbackup with command: /Users/sergei/percona/repo/xb20-log-block-size/test/../src/xtrabackup_55 --defaults-file="/Users/sergei/percona/repo/xb20-log-block-size/test/var/my.cnf" --defaults-group="mysqld" --prepare --target-dir=/Users/sergei/percona/repo/xb20-log-block-size/test/var/full_backup --apply-log-only

/Users/sergei/percona/repo/xb20-log-block-size/test/../src/xtrabackup_55 version 2.0.0 for Percona Server 5.5.16 osx10.7 (i386) (revision id: undefined)
xtrabackup: cd to /Users/sergei/percona/repo/xb20-log-block-size/test/var/full_backup
xtrabackup: This target seems to be not prepared yet.
xtrabackup: No valid checkpoint found.
xtrabackup: Error: xtrabackup_init_temp_log() failed.
innobackupex: Error:
innobackupex: ibbackup failed at /Users/sergei/percona/repo/xb20-log-block-size/test/../innobackupex line 374.
2012-06-14 12:55:59: bug976945.sh: ===> innobackupex failed with exit code 1

Will try to fix it by making auxiliary function to set log_block_size and call that function from xtrabackup_init_temp_log when prepare and from innodb_init_param in other cases.

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PXB-849