When you first encounter LiteSpeed Web Server (LSWS), choosing the right license or even the right LSWS edition can be difficult. This wiki will explain the differences between different editions and licenses (focusing more on licenses) and then go over some ways to help decide which license is right for you.
There are three different editions of LiteSpeed Web Server. (See the feature comparison on the main site for an in-depth comparison.)
LiteSpeed Web Server Enterprise Edition has 6 different licenses to choose from. These licenses reflect how much power LiteSpeed Web Server will be given. Generally, the licenses are divided by how many cores LSWS will have access to, though there are two special, more affordable licenses only for VPSs.
Notes: VPS and Ultra VPS licenses will not install on a dedicated server or a VPS over their respective RAM limits. If the concurrent connection limit is surpassed, extra connections will be queued until there is room in the connection limit. Currently supported VPS platforms are KVM, HyperV, Virtuozzo, OpenVZ VPS, XEN, VMWare and UserModeLinux VPS.
You do NOT need to buy a license to match the number of CPUs or cores on your physical server. The number of CPUs in the license title simply denotes the number of cores the LSWS process will be able to utilize. LSWS is fast and lightweight enough to run very, very well on only a fraction of the server's cores. In almost all cases, you are better off buying a license for a fraction of your server's cores and leaving the other cores for heavier processes like PHP and MySQL.
Note: Hyper-threads do NOT count towards your core total.
We offer free 15 day trial licenses. These licenses are 2-CPU licenses. Using a trial license may be a good way to figure out if LSWS is right for you and what license you want.
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 (or credited) the difference in the license fee for the remainder of the billing period.
For example, if you have a 4 core server and run LSWS, PHP, and MySQL on the same server, you will probably be best served by a 1- or 2-CPU license. LSWS is light enough that it only needs access to 1 or 2 of this server's cores. PHP and MySQL (which are much more resource intensive than LSWS) will be unaffected by this limit and will have access to all 4 of the server's cores.
Static content is served by LSWS directly, so more CPUs may help. If your server is mainly using PHP or MySQL (for instance, if it is running web applications like WordPress, etc.), giving LSWS access to more cores will not help as LSWS is not the bottleneck.
HTTPS requires more CPU power for encryption. You may find that giving LSWS access to more cores in this case improves performance. Do not overestimate this effect, though. Unless your server only serves static HTTPS, LSWS should still only have access to a fraction of the server's cores.
Some editions and licenses have a limit on the maximum number of concurrent connection you can serve. Standard Edition has a limit of 150 concurrent connections. The VPS license has a limit of 500, and the Ultra VPS a limit of 800.
If you've already installed LSWS, you can check the number of concurrent connections in the Real-Time Statistics report in the WebAdmin console.
Even without LSWS you can use the command
netstat -an | grep 80 | grep ESTA | wc -l
to check the number of concurrent connections. The number returned by this command is your current number of concurrent connections. You may be surprised how few concurrent connections you have. (For example, a forum with 3,000 users online might use 300 concurrent connections or less, as those 3,000 users do not all execute actions at the exact same split second.)