I have been trying to upgrade postgres 9.5 to 9.6 with pg_upgrade Everything seems to start fine but when pg_upgrade gets to "Copying user relation files" It takes ages to complete copying.
ie Each file like /var/lib/pgsql/9.5/data/base/24602/25140 is 1G and taking ~5-10 minutes to copyand that directory is 223G of about 990 files After a couple of hours running pg_upgrade I had to give up. looking a iotop I was seeing 99% IO load caused by [md0_raid1] and only seeing pg_upgrade go to 99% every 3-4 seconds I had no other processes using io or high cpu. Has anyone got any pointers of what could be the issue ? Ps running cp on /var/lib/pgsql/9.5/data/base/24602/25140 to my home directory is instantaneous System is Centos 7 Thanks
