ServerBuddies Support Blog

Directories in /proc

Every /proc directory contains quite a few directories named with a number. A listing of them starts off like this

These directories are called process directories, as they refer to a process’s ID and contain information specific to that process. The owner and group of each process directory is set to the user running the process. When the process is terminated, its /proc process directory vanishes. However, while the process is running, a great deal of information specific to that process is contained in the process directory’s various files.

Common groups of information concerning the kernel is grouped into directories and sub-directories within /proc.

Each of the process directories contains the following files:

cmdline — Contains the command line arguments that started the process.
cwd — A link to the current working directory for the process.
cpu — Provides specific information about the utilization of each of the system’s CPUs.
environ — Gives a list of the environment variables for the process.
exe — A link to the executable of this process.
fd — A directory containing all of the file descriptors for a particular process.
maps — Contains memory maps to the various executables and library files associated with this process.
mem — The memory held by the process.
root — A link to the root directory of the process.
stat — A status of the process.
statm — A status of the memory in use by the process.
status — Provides the status of the process in a form that is much more readable than stat or statm.

Apache configuration on Ubuntu

Apache Default Timeout

Timeout: The number of seconds before receives and sends time out.

This sets (in simple terms) the maximum time, in seconds, to wait for a request, action it and the response to the request.
The default is deliberately set high to allow for varied situations. You can reduce this to something more sane, to 30 seconds or even lower. A decrease may also help in reducing the effects of a DOS attack.
KeepAlive: Whether or not to allow persistent connections (more than one request per connection).

You should generally have KeepAlive “On” as it allows for persistent connections to a client so each file, image, etc. that gets requested. Without keepalives, the apache server and web client will need to establish new connections for every element needed to display a web page. Keeping a single connection going that the client can reuse allows your server to manage clients more efficiently.

MaxKeepAliveRequests

MaxKeepAliveRequests: The maximum number of requests to allow during a persistent connection. Set to 0 to allow an unlimited amount. We recommend you leave this number high, for maximum performance.

Since we have our persistent connection, set the maximum number of requests per connection. Keep this high for maximum performance. You might want to experiment with this setting a bit, but if you have a site with lots of images, javascript, etc, try increasing MaxKeepAliveRequests to as much as 500.

OpenLDAP server daemon slapd Installation in Ubuntu

First, install the OpenLDAP server daemon slapd and ldap-utils, a package containing LDAP management utilities:

By default slapd is configured with minimal options needed to run the slapd daemon.

The configuration example in the following sections will match the domain name of the server. For example, if the machine’s Fully Qualified Domain Name (FQDN) is ldap.example.com, the default suffix will be dc=example,dc=com.

Populating LDAP

OpenLDAP uses a separate directory which contains the cn=config Directory Information Tree (DIT). The cn=config DIT is used to dynamically configure the slapd daemon, allowing the modification of schema definitions, indexes, ACLs, etc without stopping the service.

slapd - Stand-alone LDAP Daemon

LDAP (Lightweight Directory Access Protocol) is a proposed open standard for accessing global or local directory services over a network and/or the Internet. A directory, in this sense, is very much like a phone book. LDAP can handle other information, but at present it is typically used to associate names with phone numbers and email addresses. LDAP directories are designed to support a high volume of queries, but the data stored in the directory doesn’t change very often.

OpenLDAP includes slapd (a stand-alone LDAP server), slurpd (a stand-alone LDAP replication server), libraries implementing the LDAP protocol, utilities, tools, and sample clients.

Slapd is the stand-alone LDAP daemon. It listens for LDAP connections on any number of ports (default 389), responding to the LDAP operations it receives over these connections. slapd is typically invoked at boot time, usually out of /etc/rc.local.

renice — alter priority of running processes

Renice alters the scheduling priority of one or more running processes. The following who parameters are interpreted as process ID’s, process group ID’s, or user names. a process group causes all processes in the process group to have their scheduling priority altered. a user causes all processes owned by the user to have their scheduling priority altered. By default, the processes to be affected are specified by their process ID’s.

For example,

would change the priority of process ID’s 987 and 32, and all processes owned by users daemon and root.

Users other than the super-user may only alter the priority of processes they own, and can only monotonically increase their “nice value” within the range 0 to PRIO_MAX (20). (This prevents overriding administrative fiats.) The super-user may alter the priority of any process and set the priority to any value in the range PRIO_MIN (?20) to PRIO_MAX. Useful priorities are: 20 (the affected processes will run only when nothing else in the system wants to), 0 (the “base” scheduling priority), anything negative (to make things go very fast).