Installation guide

Very Secure ftpd
191
For more information on overcommitting with KVM, refer to Chapter 20, Overcommitting with KVM.
Warning: turning off swap
Virtual memory allows Linux system to use more memory than there is physical RAM on the
system. Underused processes are swapped out which allows active processes to use memory,
improving memory utilization. Disabling swap reduces memory utilization as all processes are
stored in physical RAM.
If swap is turned off, do not overcommit guests. Overcommitting guests without any swap can
cause guests or the host system to crash.
Turning off swap
Swap usage can be completely turned off to prevent guests from being unresponsive while they are
moved back to main memory. This may improve performance but will expose the system to certain
risks.
The swapoff command can disable all swap partitions and swap files on a system.
# swapoff -a
To make this change permanent, remove swap lines from the /etc/fstab file and restart the host
system.
Using SSDs for swap
Using Solid State Drives (SSDs) for swap storage may improve the performance of virtualized guests.
Using RAID arrays, faster disks or separate drives dedicated to swap may also improve performance.
24.7. Very Secure ftpd
vsftpd can provide access to installation trees for para-virtualized guests (for example, the Red
Hat Enterprise Linux repositories) or other data. If you have not installed vsftpd during the server
installation you can grab the RPM package from your Server directory of your installation media and
install it using the rpm -ivh vsftpd*.rpm (note that the RPM package must be in your current
directory).
1. To configure vsftpd, edit /etc/passwd using vipw and change the ftp user's home directory to
the directory where you are going to keep the installation trees for your guests. An example entry
for the FTP user would look like the following:
ftp:x:14:50:FTP User:/installtree/:/sbin/nologin
2. Verify that vsftpd is not enabled using the chkconfig --list vsftpd:
$ chkconfig --list vsftpd
vsftpd 0:off 1:off 2:off 3:off 4:off 5:off 6:off
3. Run the chkconfig --levels 345 vsftpd on to start vsftpd automatically for run levels 3, 4
and 5.