R
Rob Fitzpatrick
Guest
It sounds like you don't fully understand the purpose of -bithold. I suggest you read the relevant documentation and KB articles about the BI area and BI-related parameters before making changes. The -bithold value is the limit of how large you want the BI area to grow before forward processing stops. It isn't limited by or related to system memory and it isn't necessarily related to database size. For example, you could have a 10 GB database with only 5 users and still experience significant BI growth. If one user starts a long-running transaction and the others are updating the database then once the newest BI cluster has filled, the BI area will grow. It will continue to grow until that old transaction ends, the other users' transaction activity ends, or forward processing stops e.g. due to the BI size hitting the BI threshold, or the database shutting down. The tendency of your BI area to grow is dependent on how your application code is written and, perhaps, how your users behave. If you observe its size over time there is probably some size range that it will reach that is normal for that application, but it isn't something you can pre-calculate per se. It is just a limit that you think is appropriate for your situation. What you want to avoid is a situation where the BI area grows very quickly to the point where it consumes much or all of the disk space in its partition. The BI area is both read and written to during crash recovery, meaning that it may need to grow during this phase. If your database crashes when the BI partition is full or almost full, you will not be able to complete crash recovery and open your database. The -bithold parameter lets you prevent this scenario by preventing runaway BI growth from consuming your disk space. You can also choose what happens when the database hits the threshold. If you use -bistall, the database will stall (forward processing stops) but remain up. If you don't, the database will shut down. As a rough guideline, try setting -bithold no higher than 20% of the free space in the BI partition. This assumes that the free space in that partition will be relatively constant and is segregated from other files that may grow very quickly, e.g. application or system logs. Don't rely on just -bithold to manage BI growth. It is a stopgap of last resort; you don't want your BI size to hit the threshold. You should also monitor your BI size on an ongoing basis and alert if it starts growing significantly. It is also a good idea to monitor for and alert on long-running transactions, which are an underlying cause of BI growth.
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