Handbook:Parts/Blocks/DesigningPartitionScheme/en

How many and how big
The number of partitions is highly dependent on the environment. For instance, if there are lots of users, then it is advised to have separate as it increases security and makes backups easier. If Gentoo is being installed to perform as a mail server, then should be separate as all mails are stored inside. A good choice of filesystem will then maximize the performance. Game servers will have a separate as most gaming servers are installed there. The reason is similar for : security and backups. In most situations, is to be kept big: not only will it contain the majority of applications, the Portage tree alone takes around 500 Mbyte excluding the various sources that are stored in it.

As can be seen, it very much depends on what the administrator want to achieve. Separate partitions or volumes have the following advantages:


 * Choose the best performing filesystem for each partition or volume
 * The entire system cannot run out of free space if one defunct tool is continuously writing files to a partition or volume
 * If necessary, file system checks are reduced in time, as multiple checks can be done in parallel (although this advantage is more with multiple disks than it is with multiple partitions)
 * Security can be enhanced by mounting some partitions or volumes read-only,  (setuid bits are ignored),   (executable bits are ignored) etc.

However, multiple partitions have disadvantages as well. If not configured properly, the system might have lots of free space on one partition and none on another. Another nuisance is that separate partitions - especially for important mount points like or  - often require the administrator to boot with an initramfs to mount the partition before other boot scripts start. This isn't always the case though, so results may vary.

There is also a 15-partition limit for SCSI and SATA unless the disk uses GPT labels.

What about swap space
There is no perfect value for the swap partition. The purpose of swap space is to provide disk storage to the kernel when internal memory (RAM) is under pressure. A swap space allows for the kernel to move memory pages that are not likely to be accessed soon to disk (swap or page-out), freeing memory. Of course, if that memory is suddenly needed, these pages need to be put back in memory (page-in) which will take a while (as disks are very slow compared to internal memory).

When the system is not going to run memory intensive applications or the system has lots of memory available, then it probably does not need much swap space. However, swap space is also used to store the entire memory in case of hibernation. If the system is going to need hibernation, then a bigger swap space necessary, often at least the amount of memory installed in the system.