This has worked very well for me. The sizes today (9 months later) are below. What is below contains a larger /opt/zimbra because I had not installed it when I did my original post. I am also using HSM rather agressively and have it migrate data older than 14 days every morning after backups. The devices names also show that I am using the device-mapper-multipath package for RHEL5.3, which has also been working very well.
/dev/mapper/mpath0p1 19G 4.8G 14G 27% /opt/zimbra
/dev/mapper/mpath0p2 111G 12G 97G 12% /opt/zimbra/db
/dev/mapper/mpath0p3 350G 45G 298G 14% /opt/zimbra/store
/dev/mapper/mpath0p5 28G 859M 27G 4% /opt/zimbra/redolog
/dev/mapper/mpath0p6 28G 12G 16G 42% /opt/zimbra/log
/dev/mapper/mpath0p7 56G 20G 35G 36% /opt/zimbra/index
/dev/mapper/mpath1p1 905G 282G 605G 32% /opt/zimbra/hsm
/dev/mapper/mpath2p1 1.5T 519G 933G 36% /opt/zimbra/backup |