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System Configuration—Tuning PerformanceThe various levels of RAID are described in the following list:• RAID 0 (Striped Set): This method will improve the read and write speedslightly, as read and writes span across multiple physical disks.• RAID 1 (Mirrored set): This method improves the read performance asdata will be read from multiple physical disks, but the write performance isalmost the same as non-RAID scenario.• RAID 5 (Striped set with Parity): This method improves both read and writeperformance, especially on the SMP hardware, if the software RAID is in use.You should choose a good RAID strategy that will help you improve the I/Operformance as well as the system's reliability for I/O intensive applications.NetworkDespite having performance in mind, FreeBSD has conservative defaults for theTCP/IP network stack that can be tuned to get a performance better than from thedefault configuration.There are a few sysctl variables that can be changed in order to gain better networkperformance. However, you should examine each feature to see whether it is suitablefor your environment, before deploying it on a production machine.The network related sysctl variables are stored under the net category. You cancollect the complete list of these variables along with a short description usingsysctl(8) utility:# sysctl –d netA number of important variables are explained in this chapter.TCP Delayed ACKBy default, the network stack applies 10-100 milliseconds delay before sending TCPACK message. This may lead to low performance on busy file servers (SMB protocol)or busy web servers. You can override this delay by turning off the net.inet.tcp.delayed_ack using sysctl variables:# sysctl net.inet.tcp.delayed_ack=0net.inet.tcp.delayed_ack: 1 -> 0[ 94 ]