Your first task is to allocate disk space for FreeBSD, and label that space so that sysinstall can prepare it. In order to do this you need to know how FreeBSD expects to find information on the disk.
Before you install and configure FreeBSD on your system, there is an important subject that you should be aware of, especially if you have multiple hard drives.
In a PC running a BIOS-dependent operating system such as MS-DOS® or Microsoft® Windows®, the BIOS is able to abstract the normal disk drive order, and the operating system goes along with the change. This allows the user to boot from a disk drive other than the so-called “primary master”. This is especially convenient for some users who have found that the simplest and cheapest way to keep a system backup is to buy an identical second hard drive, and perform routine copies of the first drive to the second drive using Ghost® or XCOPY . Then, if the first drive fails, or is attacked by a virus, or is scribbled upon by an operating system defect, he can easily recover by instructing the BIOS to logically swap the drives. It is like switching the cables on the drives, but without having to open the case.
More expensive systems with SCSI controllers often include BIOS extensions which allow the SCSI drives to be re-ordered in a similar fashion for up to seven drives.
A user who is accustomed to taking advantage of these features may become surprised when the results with FreeBSD are not as expected. FreeBSD does not use the BIOS, and does not know the “logical BIOS drive mapping”. This can lead to very perplexing situations, especially when drives are physically identical in geometry, and have also been made as data clones of one another.
When using FreeBSD, always restore the BIOS to natural drive numbering before installing FreeBSD, and then leave it that way. If you need to switch drives around, then do so, but do it the hard way, and open the case and move the jumpers and cables.
Note:
No changes you make at this point will be written to the disk. If you think you have made a mistake and want to start again you can use the menus to exit sysinstall and try again or press U to use the option. If you get confused and can not see how to exit you can always turn your computer off.
After choosing to begin a standard installation in sysinstall you will be shown this message:
Press Enter as instructed. You will then be
shown a list of all the hard drives that the kernel found when it
carried out the device probes.
Figure 3.13, “Select Drive for FDisk” shows an example from a
system with two IDE disks. They have been called
ad0 and ad2.
You might be wondering why ad1 is not
listed here. Why has it been missed?
Consider what would happen if you had two IDE hard disks, one
as the master on the first IDE controller, and one as the master on
the second IDE controller. If FreeBSD numbered these as it found
them, as ad0 and
ad1 then everything would work.
But if you then added a third disk, as the slave device on the
first IDE controller, it would now be ad1,
and the previous ad1 would become
ad2. Because device names (such as
ad1s1a) are used to find filesystems, you
may suddenly discover that some of your filesystems no longer
appear correctly, and you would need to change your FreeBSD
configuration.
To work around this, the kernel can be configured to name IDE
disks based on where they are, and not the order in which they were
found. With this scheme the master disk on the second IDE
controller will always be
ad2, even if there are no
ad0 or ad1
devices.
This configuration is the default for the FreeBSD kernel, which
is why this display shows ad0 and
ad2. The machine on which this screenshot
was taken had IDE disks on both master channels of the IDE
controllers, and no disks on the slave channels.
You should select the disk on which you want to install FreeBSD,
and then press .
FDisk will start, with a display similar to
that shown in Figure 3.14, “Typical fdisk Partitions Before Editing”.
The FDisk display is broken into three sections.
The first section, covering the first two lines of the display, shows details about the currently selected disk, including its FreeBSD name, the disk geometry, and the total size of the disk.
The second section shows the slices that are currently on the
disk, where they start and end, how large they are, the name FreeBSD
gives them, and their description and sub-type. This example shows two
small unused slices, which are artifacts of disk layout schemes on the
PC. It also shows one large FAT slice, which
almost certainly appears as C: in
MS-DOS® / Windows®, and an extended slice, which may contain other
drive letters for MS-DOS® / Windows®.
The third section shows the commands that are available in FDisk.
What you do now will depend on how you want to slice up your disk.
If you want to use FreeBSD for the entire disk (which will delete
all the other data on this disk when you confirm that you want
sysinstall to continue later in the
installation process) then you can press A, which
corresponds to the option.
The existing slices will be removed, and replaced with a small area
flagged as unused (again, an artifact of PC disk
layout), and then one large slice for FreeBSD. If you do this, then
you should select the newly created FreeBSD slice using the arrow
keys, and press S to mark the slice as being
bootable. The screen will then look very similar to
Figure 3.15, “Fdisk Partition Using Entire Disk”. Note the
A in the Flags column, which
indicates that this slice is active, and will be
booted from.
If you will be deleting an existing slice to make space for FreeBSD then you should select the slice using the arrow keys, and then press D. You can then press C, and be prompted for size of slice you want to create. Enter the appropriate figure and press Enter. The default value in this box represents the largest possible slice you can make, which could be the largest contiguous block of unallocated space or the size of the entire hard disk.
If you have already made space for FreeBSD (perhaps by using a tool such as PartitionMagic®) then you can press C to create a new slice. Again, you will be prompted for the size of slice you would like to create.
When finished, press Q. Your changes will be saved in sysinstall, but will not yet be written to disk.
You now have the option to install a boot manager. In general, you should choose to install the FreeBSD boot manager if:
You have more than one drive, and have installed FreeBSD onto a drive other than the first one.
You have installed FreeBSD alongside another operating system on the same disk, and you want to choose whether to start FreeBSD or the other operating system when you start the computer.
If FreeBSD is going to be the only operating system on this machine, installed on the first hard disk, then the boot manager will suffice. Choose if you are using a third-party boot manager capable of booting FreeBSD.
Make your choice and press Enter.
The help screen, reached by pressing F1, discusses the problems that can be encountered when trying to share the hard disk between operating systems.
If there is more than one drive, it will return to the Select Drives screen after the boot manager selection. If you wish to install FreeBSD on to more than one disk, then you can select another disk here and repeat the slice process using FDisk.
Important:
If you are installing FreeBSD on a drive other than your first, then the FreeBSD boot manager needs to be installed on both drives.
The Tab key toggles between the last drive selected, , and .
Press the Tab once to toggle to the , then press Enter to continue with the installation.
You must now create some partitions inside each slice that you
have just created. Remember that each partition is lettered, from
a through to h, and that
partitions b, c, and
d have conventional meanings that you should adhere
to.
Certain applications can benefit from particular partition schemes, especially if you are laying out partitions across more than one disk. However, for this, your first FreeBSD installation, you do not need to give too much thought to how you partition the disk. It is more important that you install FreeBSD and start learning how to use it. You can always re-install FreeBSD to change your partition scheme when you are more familiar with the operating system.
This scheme features four partitions—one for swap space, and three for filesystems.
| Partition | Filesystem | Size | Description |
|---|---|---|---|
a | / | 1 GB | This is the root filesystem. Every other filesystem
will be mounted somewhere under this one. 1 GB is a
reasonable size for this filesystem. You will not be storing
too much data on it, as a regular FreeBSD install will put
about 128 MB of data here. The remaining space is for
temporary data, and also leaves expansion space if future
versions of
FreeBSD need more space in /. |
b | N/A | 2-3 x RAM | The system's swap space is kept on the If you have more than one disk then you can put swap space on each disk. FreeBSD will then use each disk for swap, which effectively speeds up the act of swapping. In this case, calculate the total amount of swap you need (e.g., 128 MB), and then divide this by the number of disks you have (e.g., two disks) to give the amount of swap you should put on each disk, in this example, 64 MB of swap per disk. |
e | /var | 512 MB to 4096 MB | The /var directory contains
files that are constantly varying;
log files, and other administrative files. Many
of these files are read-from or written-to extensively during
FreeBSD's day-to-day running. Putting these files on another
filesystem allows FreeBSD to optimize the access of these
files without affecting other files in other directories that
do not have the same access pattern. |
f | /usr | Rest of disk (at least 8 GB) | All your other files will typically be stored in
/usr and its subdirectories. |
Warning:
The values above are given as example and should be used
by experienced users only. Users are encouraged to use the
automatic partition layout called Auto
Defaults by the FreeBSD partition editor.
If you will be installing FreeBSD on to more than one disk then you must also create partitions in the other slices that you configured. The easiest way to do this is to create two partitions on each disk, one for the swap space, and one for a filesystem.
| Partition | Filesystem | Size | Description |
|---|---|---|---|
b | N/A | See description | As already discussed, you can split swap space across
each disk. Even though the a partition is
free, convention dictates that swap space stays on the
b partition. |
e | /diskn | Rest of disk | The rest of the disk is taken up with one big partition.
This could easily be put on the a
partition, instead of the e partition.
However, convention says that the a
partition on a slice is reserved for the filesystem that will
be the root (/) filesystem. You do not
have to follow this convention, but
sysinstall does, so following it
yourself makes the installation slightly cleaner. You can
choose to mount this filesystem anywhere; this example
suggests that you mount them as directories
/disk, where
n is a number that changes for each
disk. But you can use another scheme if you prefer. |
Having chosen your partition layout you can now create it using sysinstall. You will see this message:
Press Enter to start the FreeBSD partition editor, called Disklabel.
Figure 3.18, “Sysinstall Disklabel Editor” shows the display when you first start Disklabel. The display is divided in to three sections.
The first few lines show the name of the disk you are currently
working on, and the slice that contains the partitions you are
creating (at this point Disklabel calls
this the Partition name rather than slice name).
This display also shows the amount of free space within the slice;
that is, space that was set aside in the slice, but that has not yet
been assigned to a partition.
The middle of the display shows the partitions that have been created, the name of the filesystem that each partition contains, their size, and some options pertaining to the creation of the filesystem.
The bottom third of the screen shows the keystrokes that are valid in Disklabel.
Disklabel can automatically create partitions for you and assign them default sizes. The default sizes are calculated with the help of an internal partition sizing algorithm based on the disk size. Try this now, by Pressing A. You will see a display similar to that shown in Figure 3.19, “Sysinstall Disklabel Editor with Auto Defaults”. Depending on the size of the disk you are using, the defaults may or may not be appropriate. This does not matter, as you do not have to accept the defaults.
Note:
The default partitioning assigns
the /tmp directory its own partition instead
of being part of the / partition. This
helps avoid filling the / partition with
temporary files.
If you choose to not use the default partitions and wish to replace them with your own, use the arrow keys to select the first partition, and press D to delete it. Repeat this to delete all the suggested partitions.
To create the first partition (a, mounted as
/ — root), make sure the proper disk slice
at the top of
the screen is selected and press C. A dialog box
will appear prompting you for the size of the new partition (as shown
in Figure 3.20, “Free Space for Root Partition”). You can enter the size as
the number of disk blocks you want to use, or as a
number followed by either M for megabytes,
G for gigabytes, or C for
cylinders.
The default size shown will create a partition that takes up the
rest of the slice. If you are using the partition sizes described
in the earlier example, then delete the existing figure using
Backspace, and then type in
512M, as shown in
Figure 3.21, “Edit Root Partition Size”. Then press
.
Having chosen the partition's size you will then be asked whether this partition will contain a filesystem or swap space. The dialog box is shown in Figure 3.22, “Choose the Root Partition Type”. This first partition will contain a filesystem, so check that is selected and press Enter.
Finally, because you are creating a filesystem, you must tell
Disklabel where the filesystem is to be
mounted. The dialog box is shown in
Figure 3.23, “Choose the Root Mount Point”. The root filesystem's mount
point is /, so type /, and
then press Enter.
The display will then update to show you the newly created
partition. You should repeat this procedure for the other
partitions. When you create the swap partition, you will not be
prompted for the filesystem mount point, as swap partitions are never
mounted. When you create the final partition,
/usr, you can leave the suggested size as is, to
use the rest of the slice.
Your final FreeBSD DiskLabel Editor screen will appear similar to Figure 3.24, “Sysinstall Disklabel Editor”, although your values chosen may be different. Press Q to finish.
