Web ADC

License Types

LiteSpeed Web ADC has a few different license options to choose from. These licenses reflect how much power LiteSpeed Web ADC will be given. The licenses are divided by how many worker processes are spawned in each.

Type Worker Processes
Web ADC Small 1
Web ADC Medium 2
Web ADC Large 4
Web ADC Ultimate Configurable

How to Choose a License

Our Recommendation

We recommend the license have enough worker processes to make use of roughly 25% of your server's cores.

Example

If you have a server with 4 cores, start with a Web ADC Small license.

What is a worker process?

The number of worker processes describes the number of processes that do general server work. Examples of the work done include: routing requests, SSL decryption/encryption, caching, rewriting, etc.

LiteSpeed will fork that number of processes. Each process will utilize a separate core.

Factors to Consider

  • You can always upgrade or downgrade.

Often, finding exactly the right license for your usage is a matter of trial and error. Different sites put pressure on different parts of the server. The best approach may be to purchase a license, then try upgrading or downgrading to see if it affects your service noticeably. You can upgrade or downgrade at any time and you will only be charged the difference in the license fee for the remainder of the billing period.

  • Do you have a high volume of HTTPS traffic?

HTTPS requires more CPU power for encryption. You may find that giving LSADC access to more cores in this case will improve performance. Do not overestimate this effect though. Unless you have an extremely high amount of traffic that visits cached HTTPS files, LSADC should still only need a couple cores.

  • Have you tried a trial license?

A trial license is the best way to get an idea of what license type is right for you.

Indicators You Need to Upgrade

A top command will reveal important information about how much resources different processes are taking on your server. (LSADC's process is called lslbd.) A couple of these outputs are useful for determining if your installation of LSADC needs access to more cores:

  • %CPU - Generally LSADC's CPU usage is low. If LSADC's CPU usage starts climbing, and especially if it climbs while your overall load is low, it can indicate that LSADC is hitting a bottleneck and would benefit from access to more cores.
  • %wa - High I/O wait can also be an indicator that LSADC needs more worker processes (and thus access to more cores).

Last update: April 27, 2020