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Perfect sysctl.conf

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  • Perfect sysctl.conf

    Hi.

    Been googling like crazy for sysctl tweaks which would be suitable for a loaded database system but have not found any why I'm turning to the forum.

    I've created a quite nice sysctl.conf which I use with my lighttpd webservers but want something tweaked for databases.

    I guess the vm should be tweaked in regards to overcommit etc and as well the net buffers but I'm not sure where to start.

    Anyone ?

    # Tcp memory
    net.core.rmem_max=16777216
    net.core.wmem_max=16777216
    net.ipv4.tcp_rmem=4096 87380 16777216
    net.ipv4.tcp_wmem=4096 65536 16777216
    # Increase the number of incoming connections that can queue up before dropping
    net.core.somaxconn = 262144

    # Big queue for the network device
    net.core.netdev_max_backlog=30000

    # Apache Scaling suggests 1000 ?
    net.ipv4.tcp_max_orphans = 262144
    net.ipv4.tcp_max_syn_backlog = 262144
    net.ipv4.tcp_synack_retries = 2
    net.ipv4.tcp_syn_retries = 2
    # Lots of local ports for connections
    net.ipv4.tcp_max_tw_buckets = 1000000
    net.ipv4.ip_local_port_range = 1024 65000
    net.ipv4.tcp_sack = 1
    net.ipv4.tcp_keepalive_time = 300
    net.ipv4.tcp_synack_retries = 0

    # These ensure that TIME_WAIT ports either get reused or closed fast.
    net.ipv4.tcp_fin_timeout = 1
    net.ipv4.tcp_tw_recycle = 1

    # Security
    net.ipv4.tcp_syncookies = 1
    net.ipv4.tcp_rfc1337 = 1

    # Disables IP source routing
    net.ipv4.conf.all.accept_source_route = 0
    net.ipv4.conf.lo.accept_source_route = 0
    net.ipv4.conf.eth0.accept_source_route = 0
    net.ipv4.conf.eth1.accept_source_route = 0
    net.ipv4.conf.default.accept_source_route = 0

    # Decrease the time default value for tcp_fin_timeout connection
    net.ipv4.tcp_fin_timeout = 30

    # Tuning the FS
    fs.file-max = 5049800

    # Tuning the VM - According to http://kb.pert.geant2.net/PERTKB/ApacheScaling
    vm.min_free_kbytes = 204800
    vm.page-cluster = 20
    # Apache tuning suggests 200...
    vm.swappiness = 10

  • #2
    Quote:


    net.core.rmem_max=16777216
    net.core.wmem_max=16777216
    net.ipv4.tcp_rmem=4096 87380 16777216
    net.ipv4.tcp_wmem=4096 65536 16777216



    Well,.. I am not an experienced Syscontroll optimizer... but aren't this number a little bit big?

    16777216 = 16 MB,.. this is enough for a 1280 MBit/s connection with a RTT of 100ms... Just to remember, default is 128K !

    Quote:


    # Increase the number of incoming connections that can queue up before dropping
    net.core.somaxconn = 262144

    When do you plan to answer the connections... if you queue so many up?


    The same for the other numbers...
    The default might not be ideal, but yours a so big, i don't know if it really help increasing performance?!?

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