Trouble importing xar after codepage switch / maximum attachment size

Hello, I have an xwiki installation on a virtual server. As default, the jvm on that machine has only 64mb as -Xmx which causes xwiki to crash on attachment of more than 1,3 mb. Therefore i increased the xms and xms values by setting them in /etc/bash.bashrc: export JAVA_OPTS="-Xms256m -Xmx256m" I enountered problems errors 3232 and 3231) when i restarted xwiki after having changed the codepage (-Dfile.encoding). Even though i ended up with the same codepage that i used in the beginning, it was no longer possible to access the attachments. Importing .xar files that i made in advance as backups didn't work, either. Attachments are still displayed with the articles, where authors set them, but the cannot beretrieved. To avoid the error messages when trying to upload the attachments again, i deleted the entries in the xwikiattachments_archive and xwikiattachments_content tables. Now, when i upload the same files again, the are not versioned but added as additional attachment. Is it ok to delete the rows in the tables xwikiattachment_archive and xwikiattachment_content or should i delete xwikiattachment, too? Are there other conflicts probable to arise from this direct db manipulation? Regards Thomas