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how_to:database_issues [2010/09/21 09:43] – paul | how_to:database_issues [2013/08/30 12:37] – paul | ||
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======Database Issues====== | ======Database Issues====== | ||
- | VPOP3 version 3 and later use the [[http:// | + | VPOP3 version 3 and later use the [[http:// |
- | =====Disk Caching===== | + | * [[Database & Disk Caching]] |
- | + | | |
- | One key point is that, like all other high-end databases, PostgreSQL should not be run on a server with disk level [[http:// | + | * [[VPOP3DB/ |
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- | High-end RAID controllers often contain a battery backed write cache (BBWC) - in this case, if the power fails, the cached data is held in battery powered memory until the power is restored. After power is restored the cached data will be written to disk. In this case, using write back caching through the BBWC is perfectly safe (as long as power is not left off for so long that the batteries run down). | + | |
- | + | ||
- | It is slightly less safe, but still usually OK, to have a UPS with automated shutdown of the PC. You still have to ensure that the PC is not just turned off without shutting down properly. | + | |
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- | If you don't have either of these facilities, then make sure you turn off write-back caching in Windows. | + | |
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- | Exactly how you turn off write-back caching depends on your version of Windows, and the disk controller. | + | |
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- | The instructions below are for Windows 7 with standard SATA disks | + | |
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- | | + | |
- | - Under **Disk Drives** find the hard disk that VPOP3 is installed on, and right-click it and choose **Properties**\\ {{: | + | |
- | - Go to the **Policies** tab. Turn off **Enable write caching onthe device** and press **OK**\\ {{: | + | |
- | + | ||
- | =====Possible Conflicting Software===== | + | |
- | We strongly recommend that virus scanners exclude the VPOP3\pgsql\data folder and all subfolders. If a virus scanner decides to quarantine a file from within this folder structure, that can cause VPOP3 not to run, and could lead to data loss or corruption. | + | |
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- | We also recommend that backup software does not backup this folder structure. If a backup program opens a file for backup, and then the database server needs it, it can cause problems, and crashes. | + | |
=====Database corruption===== | =====Database corruption===== | ||
- | If VPOP3 won't start even though the process is running, then that is often because the PostgreSQL service is not running. If the PostgreSQL service won't start, or keeps crashing, then it is probably because the database is corrupted. | + | If VPOP3 won't start even though the process is running, then that is often because the PostgreSQL service is not running. If the PostgreSQL service won't start, or keeps crashing, then it is probably because the database is corrupted. |
* [[Restore a database backup|Restoring a database]] | * [[Restore a database backup|Restoring a database]] | ||
- | * [[PostgreSQL server won't start due to damaged log files]] | + | * [[PostgreSQL server won't start due to damaged log files]] |
* [[Total Rebuild of Database]] | * [[Total Rebuild of Database]] | ||
+ | * [[Repairing corrupted database]] | ||
+ | |||
+ | Our chargeable support service will be able to help with this if necessary. Note that we cannot guarantee recovering data, as that will depend on how badly the database has been damaged, and when the latest good backup was. | ||