There are unfinished transactions remaining. You might consider running yum-complete-transaction first to finish them.

実行中のyumのトランザクションが残っているので yum-complete-transaction せよとのこと。昨日サーバのバックアップのことで色々と作業していたのが原因かも・・

[root@server1 ~]# yum-complete-transaction

yum update してみる

[root@server1 ~]# yum update
Loaded plugins: downloadonly, fastestmirror, priorities, refresh-packagekit, security
Loading mirror speeds from cached hostfile
* base: ftp.tsukuba.wide.ad.jp
* centosplus: ftp.tsukuba.wide.ad.jp
* epel: mirror01.idc.hinet.net
* extras: ftp.tsukuba.wide.ad.jp
* updates: ftp.tsukuba.wide.ad.jp
99 packages excluded due to repository priority protections
Setting up Update Process
No Packages marked for Update