UNIX for Dummies Questions & Answers

Problem: receiving error message:
WARNING: /tmp: File system full, swap space limit exceeded

/tmp becomes full when the following quasi equation looks like this for your
system:
((ram + swap - processes) * .9) - files_in_/tmp = 0
| | | | |
| ---------- | /tmp (avail)
| | |
| virtual memory |
| |
-------------------------------
|
/tmp (total)

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There are many things that can be done to remedy the problem, among them;
1. add more ram
2. add more swap
3. kill processes
4. delete files in /tmp

A fast and simple solution to add more swap is to create a swap file
and add it to the existing swap:

#mkfile <megs>m <path_to_filesystem_with_plenty_of_space>/swap
#swap -a <path_to_filesystem_with_plenty_of_space>/swap

Example:

#mkfile 20m /newdir/swapfile
#swap -a /newdir/swapfile

To make this swap space available (add the swap file to virtual memory) each
time the system is rebooted, add a line in the /etc/vfstab.

#device device mount FS fsck mount mount
#to mount to fsck point type pass at boot options
...
/swapfile - - swap - no -

This is inefficient though. Filesystems waste space for administrative reasons
(about 10%). They are slower than accessing raw disk too.
It is better to use a raw disk parition as a swap file.

There may be plenty of virtual memory. The problem could be that some processes
are simply using too much swap and need to be killed/restarted. Some badly
written/configured programs will take up all available memory no matter how
much of it is available.

The see which processes are using the most memory run the following command:

# /usr/bin/ps -el | sort -rn -k 10
8 S 52475 2594 345 0 40 20 60b1adc0 17325 6098872e ? 57:24 Xsun
8 S 52475 8111 8092 0 51 20 60d6efa0 3882 61915dfe pts/4 1:06 sotool
8 S 52475 9054 19313 0 51 20 60d07658 1568 pts/6 0:26 dtmail
8 S 0 3211 1 1 43 20 609f2038 1207 60989a16 ? 66:41 esd
8 S 0 3213 1 0 40 20 6095c6e0 1146 60989a66 ? 27:01 esd
8 S 52475 2739 2728 0 51 20 60cea208 1128 60b2a0c6 ? 0:01 nametool
^
The above ps output is sorted by process size. |
The biggest offenders are at the top. |
The 10th column is the process size in pages. _______|

To see how big a page is in kbytes, run the pagesize command:
# pagesize
8192

From Sunsolve:
The first disk on a Sun system is typically sectioned off into three or more
partitions. Of these, the root (/) partition is typically the smallest, and
yet often the most active, accommodating files for incoming mail, print spooling,
and temporary work files for the programs that run on your system.

With all this activity in the directories stored on the root partition, it isn't
surprising that you sometimes may see system messages such as:
vmunix: / file system full

Or messages from an application such as:
Not enough space in /tmp

Following are instructions for getting around these problems, and for making
the root partition larger.



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Solving Space Problems with Symbolic Links
------------------------------------------
Many applications create large temporary files in the /tmp and /var/tmp
directories, and one easy way to make more room in the root partition is to
send temporary files to a directory on a different partition.

For example, many people set up a symbolic link from these directories to
/usr/tmp, which is part of the /usr partition and generally has much more
room.

Here are the steps:

1. Quit any running applications.
Applications such as MailTool often keep work files in /tmp or /var/tmp.
You'll be temporarily deleting the files in these directories, so you should
quit applications that may use them.

2. Become superuser
Use the su command to become superuser.
% su

3. Delete the /tmp and /usr/tmp directories.
Use the following commands:
# rm -r /tmp
# rm -r /usr/tmp

NOTE: All contents will be deleted.

4. Set up the symbolic links to /usr/tmp
# ln -s /usr/tmp /tmp
# ln -s /usr/tmp /var/tmp

5. Make the temporary directories writable.
Use the chmod command to open the permissions of the two linked
directories:
# chmod 777 /tmp /var/tmp


Solving Space Problems by Repartitioning
----------------------------------------
In some cases, it may make sense to enlarge the size of the root partition. For
example, if you typically keep many long messages in your incoming mail box,
your mail may be consuming a large portion of the root partition.

The only way to increase the size of the root partition is to redivide the disk
into new sections. This procedure is known as repartitioning.

Before You Begin Repartitioning

Caution - Enlarging your a partition wipes out any information you have
stored on that partition. Unless this system is brand new, you should make
certain you have backups of any important files on the system. Back up the
entire disk. See System and Network Administration for instructions on making
backups.

Steps to Enlarge the Root Partition

To enlarge the root partition, use the format(8S) utility from the 4.1 Release
tape.

1. Boot the format utility from the first 4.1 Release tape.
Follow instructions in the System and Network Administration manual,
Appendix A.


2. Start format, choose "partition."
Once MUNIX has been loaded, run format and select the "partition"
program:
# format

Format Menu:
disk - select a disk
type - select (define) a disk type
partition - select (define) a partition table
current - describe the current disk
format - format the disk
repair - repair a defective sector
show - show a disk address
label - label the disk
analyze - surface analysis
defect - defect list management
backup - search for backup labels
quit

format> partition

3. Change the size of the "a" partition
Type a and press Return to enter new values for partition a:

PARTITION MENU:
a - change `a' partition
b - change `b' partition
c - change `c' partition
d - change `d' partition
e - change `e' partition
f - change `f' partition
g - change `g' partition
h - change `h' partition
select - select a predefined table
name - name the current table
print - display the current table
label - write partition map and label to the disk
quit

partition> a


4. Specify the starting cylinder and blocks.
The format utility deals areas of the disk in terms of "blocks." To convert
megabytes to blocks, multiply the number of megabytes by 2048. For
instance, if you want a partition of exactly 16MB, multiply 16 X 2048 =
32,768 blocks.

partition a - starting cyl 0, # blocks 32025 (61/0/0)

Enter new starting cyl [0]: <Return>
Enter new # blocks [32025, 61/0/0]: 32768

partition> a


5. Check for an even cylinder boundary.
All partitions should end on even cylinder boundaries-the track and block
numbers should be 0. For example, the following partition ends evenly at
cylinder 63:

63 / 0 / 0 = cylinders/tracks/blocks

If a partition does not start on an even cylinder boundary (as below, for
instance), chose the partition again from the menu and specify a new
number of blocks:

partition> a

partition a - starting cyl 0, # blocks 32768 (62/6/8)

Enter new starting cyl [0]: <Return>

Enter new # blocks [32768, 62/6/8]: 63/0/0


6. Adjust the adjacent partition
Because you have changed the size of partition "a", you must adjust the
starting cylinder for the adjacent partition (partition "b").

Also check that the partition begins on an even cylinder boundary, and
adjust the starting cylinder as necessary:

partition> b

partition b - starting cyl 63, # blocks 49152 (93/9/12)

Enter new starting cyl [63]: <Return>

Enter new # blocks [49152, 93/9/12]: 94/0/0

partition> quit


7. Label the drive.
After repartitioning the disk you must relabel the disk in order for the label
to reflect the changes. Use the "label" option from the main format menu.

Note that you can use the SunInstall program instead of format (8S) to change
the size of any partitions other than root or swap. (Though you can also use
SunInstall to enlarge the swap partition, the easier way to increase swap space
is through the swapon command.)

8. Run SunInstall.
Reboot from the tape or CD and rerun SunInstall to set up the system.

9. Restore your files.
If you backed up files before repartitioning, restore those files.


Additional Information on Repartitioning

Note: For detailed information regarding format(8S) see the System and
Network Administration manual, Appendix A.

Useful search terms in AnswerBook[TM] include:

partition repartition sd0a xd0a format