In Maximum MySQL Database Size? Nick Duncan wants to find out what the maximum size of his MySQL database can possibly be. He answers that with a list of maximum file sizes per file system type. That is not a useful answer.

While every file system does have a maximum file size, this limitation is usually not relevant when it comes to MySQL maximum database size. But let's start with file systems, anyway.

First: You never want to run a database system on a FAT filesystem, ever. In FAT, a file is a linked list of blocks in the FAT. That is, certain "seek" (backwards seek operations) operations become slower the larger a file is, because the file system has to position the file pointer by traversing the linked list of blocks in the FAT. Since seek operations are basically what a large database does all day, FAT is completely useless for this. So the actual file size limit of FAT is kind of moot for the purpose of this discussion.

Second: You also never want to run a database system on a 32 bit operating system. Not only does that limit your file size in Windows and also in certain ways in Linux, it will also limit the amount of system memory you can invest into MySQL buffer caches. That's kind of useless, because it is memory that makes databases fast.

In 64 bit systems and with modern file systems (NTFS in Windows and XFS on LVM2 in Linux, on a recent kernel), the operating imposed file size limit is multiple terabytes or petabytes, even. We will soon see that the exact number is not really relevant.


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