Need to install some perl module :

yum -y install perl-JSON perl-Statistics-Descriptive perl-IPC-System-Simple

Update script :
cd BackupPC-Check
git pull ; \cp -vu Check.pm /usr/share/BackupPC/lib/BackupPC/CGI/Check.pm ; \cp -vu en.pm /usr/share/BackupPC/lib/BackupPC/Lang/en.pm

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TOO SMALL :

(new_size.last > new_size_q3.last + new_size_q3.last - new_size_q1.last) * 1.5 and new_size.last > new_size_avg.last*6

TOO BIG :
(last=1 and last>4 and new_size.last < new_size_q1.last - new_size_q3.last - new_size_q1.last) * 1.5 and new_size.last < new_size_avg.last/3