sendmail, 4th Edition

Multiple Queue Directories

V8.10 sendmail offers the ability to distribute queued messages across multiple directories. In general, this is a good idea. If, for example, a high volume of email is stressing your current disk, you can improve efficiency by using multiple queue directories spread over multiple disks and controllers.

To illustrate, we will set up a machine that has three brand-new disks to use as multiple queue directories. The disks have already been formatted and a filesystem has been placed on each. We next create directories on which to mount them:

# mkdir /var/queues /var/queues/q.1 /var/queues/q.2 /var/queues/q.3
# chmod 700 /var/queues /var/queues/q.?

Because of the way multiple queue directories are implemented inside sendmail, the queue directory names must differ only in their suffixes, hence the trailing 1, 2, and 3. First the directories are created with mkdir(1) or a symbolic link, and then the permission on each is reduced to readable and writable only by root for security reasons. Note that these are the permissions after all queue disks are mounted.

Next, arrange for the disks to be mounted by placing the appropriate entries in /etc/fstab or /etc/vfstab. Here, we illustrate with the partial contents of /etc/fstab for Linux:

/dev/hda2         /var/queues/q.1     ext2     defaults    1 1
/dev/hdb1         /var/queues/q.2     ext2     defaults    1 1
/dev/hdc1         /var/queues/q.3     ext2     defaults    1 1

Note that we are mounting a separate disk on each queue directory. Your disk device names will doubtless ...