Code For Food

Category: notes

  • Update maxmind geoip database for iplocation splunk command

    If you are using outdated maxmind db in your splunk version, you will see some of the location is not right for a few IPs. Follow these steps to update the maxmind GeoLite2-City db file:

    1. You can go to this site, http://dev.maxmind.com/geoip/geoip2/geolite2/
    2. Download GeoLite2-City.mmdb
    3. Replace it with $SPLUNK_HOME/share/GeoLite2-City.mmdb, usually at /opt/splunk/share in any Linux host
    4. Don’t need to restart splunk, run new query in splunk and the db will be refreshed itself.

  • Force redirect to HTTPS

    RewriteEngine On
    RewriteCond %{HTTP:X-Forwarded-Proto} !https
    RewriteRule ^.*$ https://%{SERVER_NAME}%{REQUEST_URI}

  • Best size for swap partition in Linux

    The old rule: Swap size should be twice of the RAM is only applicable in the old system when RAM is small (<1GB)

    The new rule:
    Swap = Equal RAM size (if RAM < 2GB)
    Swap = 2GB size (if 2GB < RAM < 8GB)
    Swap = 0.5 RAM size (if RAM > 8GB)

    There is no benefit to put the swap size twice as RAM > 2GB since a system using up to mutiple GBs in swap memory should not be a good design for performance.

  • Mongodump reads from secondary by default in shard cluster with replica set

    When running mongodump against a mongos instance where the sharded cluster consists of replica sets, the read preference of the operation will prefer reads from secondary members of the set.

  • MongoDB MMS Point In Time restores are only available for the last 24 hours.

    Error: When restoring DB for replica set using MMS point in time, we have this error:

    “You are attempting to restore to a version no longer accessible for restore. Point In Time restores are only available for the last 24 hours.”

    Causes: Allow point-in-time restores going back (or oplog stored time) is set to more than 1 day but the snapshots interval is more than 12 hours (min 12 hours for Point in Time to work)

    Solutions: Allow point-in-time restores going back should be set to more than 1 days but the snapshot should be also captured at least every 12 hours

    Notes: Point in time only works for replica set. If you are using shard cluster, you should use checkpoint restore which allows to restore to any 15 mins point in time.