Hi,
I now was able to reproduce the issue on my test Linux system.
Here's snippet from my liveupdt.log file:
=------
2014/11/11 8:31:03 Loading guard file: /tmp/1415662261310/spe$20av$20definitions$20for$20x86$2dlinux_7.0_symalllanguages_livetri.zip1415662263225/liveupdt.grd
2014/11/11 8:31:03 FreeSpace available on /tmp/1415662261310 is 273216 KB.
2014/11/11 8:31:03 Disk space check for 1415570926jtun_ennluap2.lin failed. Requested free space was .
2014/11/11 8:31:03
2014/11/11 8:31:03 The Java LiveUpdate session did not complete successfully.
2014/11/11 8:31:03 Return code = 246
<snip>
<IdsSecurityGuardLoad></2Ftmp/2F1415662261310/2Fspe$20av$20definitions$20for$20x86$2dlinux_7.0_symalllanguages_livetri.zip1415662263225/2Fliveupdt.grd>
<IdsDiskSpaceFail><1415570926jtun_ennluap2.lin><2369.049292564392>
<IdsJavaSessionFailure>
<IdsJavaSessionReturnCode><246>
=------2,369.049 (in MB)
The log file should have "FreeSpace available on ...." line to indicate the free space LiveUpdate has recognized. So you should recheck your liveupdt.log file.
It should have at least the file size to download, e.g. "2,369.049 (in MB)" with above log file, plus 1GB for unzipping the files.
BTW, about SEP, it is always good idea to exclude LiveUpdate workdir folder and Scan Engine installation folder from scanning with AntiVirus softwares, as it will cause mishap on some situations.
Regards,
Haro