dockerでCentOS6を使うときにyum update が遅かった

docker でcentos6 を使ってyum update したら異様に遅かったので、

# docker run -t -i centos:centos6 /bin/bash
bash-4.1# 
bash-4.1# yum update
Loaded plugins: fastestmirror                                                                                                               
base                                                                                                                                        | 3.7 kB     00:00
base/primary_db                                                                                                                             | 4.4 MB     00:00
extras                                                                                                                                      | 3.3 kB     00:00
extras/primary_db                                                                                                                           |  19 kB     00:00
libselinux                                                                                                                                  | 3.4 kB     00:00
libselinux/primary_db                                                                                                                       | 2.7 MB     00:00
updates                                                                                                                                     | 3.4 kB     00:00
updates/primary_db                                                 13% [=======                                                  ] 5.8 kB/s | 708 kB     13:29 ETA  

5.8kB/sなり。 遅すぎなのでCTL-cしたら

 Current download cancelled, interrupt (ctrl-c) again within two seconds
to exit.  

http://mirrors.yun-idc.com/centos/6.5/updates/x86_64/repodata/da7d5b44fca19c924b160677a95fc8ef5cce450991c1a37a5cbbf513e36f310a-primary.sqlite.bz2: [Errno 14] PYC
URL ERROR 22 - "The requested URL returned error: 404 Not Found"
Trying other mirror.
http://centos.mirror.cdnetworks.com/6.5/updates/x86_64/repodata/da7d5b44fca19c924b160677a95fc8ef5cce450991c1a37a5cbbf513e36f310a-primary.sqlite.bz2: [Errno 14] PYC
URL ERROR 22 - "The requested URL returned error: 404 Not Found"
Trying other mirror.
^C

Exiting on user cancel
bash-4.1# 

cache がおかしいらしいのでクリアしたら

bash-4.1# find / | grep primary.sqlite.bz2
/var/cache/yum/x86_64/6/updates/da7d5b44fca19c924b160677a95fc8ef5cce450991c1a37a5cbbf513e36f310a-primary.sqlite.bz2
bash-4.1# 
bash-4.1# 
bash-4.1# yum clean all
Loaded plugins: fastestmirror
Cleaning repos: base extras libselinux updates
Cleaning up Everything
bash-4.1# 

スムーズになったよ

bash-4.1# yum update
Loaded plugins: fastestmirror
Determining fastest mirrors
 * base: www.ftp.ne.jp
 * extras: www.ftp.ne.jp
 * libselinux: www.ftp.ne.jp
 * updates: ftp.yzu.edu.tw
base                                                                                                                                        | 3.7 kB     00:00
base/primary_db                                                                                                                             | 4.4 MB     00:00
extras                                                                                                                                      | 3.3 kB     00:00
extras/primary_db                                                                                                                           |  19 kB     00:00
libselinux                                                                                                                                  | 3.4 kB     00:00
libselinux/primary_db                                                                                                                       | 2.7 MB     00:00
updates                                                                                                                                     | 3.4 kB     00:00
updates/primary_db                                                                                                                          | 5.3 MB     00:07
Setting up Update Process
Resolving Dependencies