10 More Discussions You Might Find Interesting
1. Solaris
Hi Solaris Folks :),
I need to calculate the swap usage on solaris server, please let me understand the output of below swap -s and swap -l commands.
$swap -s
total: 1774912k bytes allocated + 240616k reserved = 2015528k used, 14542512k available
$swap -l
swapfile dev swaplo... (6 Replies)
Discussion started by: seenuvasan1985
6 Replies
2. Solaris
Hi,
Can somebody please help here, since iam just a beginner.
According to my book knowledge.
the Avalilable memory calculated by swap -l (includes only swap) should be small as compared to swap -s value(includes Virtual memory=swap +physical).
but this is quite opposite in my case.
swap... (6 Replies)
Discussion started by: Laxxi
6 Replies
3. Red Hat
Hi,
I have added a new disk to production server. How to make it visible to os and how to configure it. I also want to add some space from that disk to swap space. Please help me out. (1 Reply)
Discussion started by: chetansingh23
1 Replies
4. HP-UX
Hi
I have an integrity machine rx7620 and rx8640 running hp-ux 11.31. I'm planning to fine tune the system:
- I would like to know when does the memory swap space spill over to the device swap space?
- And how much % of memory swap utilization should be specified (swap space device... (6 Replies)
Discussion started by: lamoul
6 Replies
5. HP-UX
I have a HP-UX B.11.23 server with 16 gb of memory 84 gb of swap configured. I am being pushed to define more swap to try and get more Tuxedo domains to start. At what point do we have too much swap for the amount of memory? Thanks in advance. (11 Replies)
Discussion started by: scotbuff
11 Replies
6. Solaris
Hello and thanks in advance.
I have a Sun box with raid 1 on the O/S disks using solaris svm.
I want to unmirror my swap partition, and add the slice on the second disk as an additional swap device. This would give me twice as much swap space.
I have been warned not to do this by some... (3 Replies)
Discussion started by: BG_JrAdmin
3 Replies
7. Solaris
When i try to type swap -l ,nothing come out but blinking.
May i know what is the problem and solutions ?
thanks (6 Replies)
Discussion started by: Farbegas
6 Replies
8. AIX
I have an unsupported legacy server:
# uname -a
AIX ibmms01 3 4 0054960A4C00
Following a period of poor performance, it was investigated using vmstat 10.
There upto 10 blocked kernel threads reported, and free memory was down to 123. The scan rate was high, 3000+ with lots of page in page... (6 Replies)
Discussion started by: jabberwocky
6 Replies
9. UNIX for Dummies Questions & Answers
Is it really so that if swap will be located in the begining of hard drive, than it will work faster? (1 Reply)
Discussion started by: Ty3
1 Replies
10. UNIX for Dummies Questions & Answers
When i re-updated my system i set my swap at 500 MB. I have 256 in ram and have never even gone into the 250 mb of swap that i had originally configured. How do I reduce the swap? (3 Replies)
Discussion started by: macdonto
3 Replies
MKSWAP(8) System Administration MKSWAP(8)
NAME
mkswap - set up a Linux swap area
SYNOPSIS
mkswap [options] device [size]
DESCRIPTION
mkswap sets up a Linux swap area on a device or in a file.
The device argument will usually be a disk partition (something like /dev/sdb7) but can also be a file. The Linux kernel does not look at
partition IDs, but many installation scripts will assume that partitions of hex type 82 (LINUX_SWAP) are meant to be swap partitions.
(Warning: Solaris also uses this type. Be careful not to kill your Solaris partitions.)
The size parameter is superfluous but retained for backwards compatibility. (It specifies the desired size of the swap area in 1024-byte
blocks. mkswap will use the entire partition or file if it is omitted. Specifying it is unwise - a typo may destroy your disk.)
After creating the swap area, you need the swapon command to start using it. Usually swap areas are listed in /etc/fstab so that they can
be taken into use at boot time by a swapon -a command in some boot script.
WARNING
The swap header does not touch the first block. A boot loader or disk label can be there, but it is not a recommended setup. The recom-
mended setup is to use a separate partition for a Linux swap area.
mkswap, like many others mkfs-like utils, erases the first partition block to make any previous filesystem invisible.
However, mkswap refuses to erase the first block on a device with a disk label (SUN, BSD, ...).
OPTIONS
-c, --check
Check the device (if it is a block device) for bad blocks before creating the swap area. If any bad blocks are found, the count is
printed.
-f, --force
Go ahead even if the command is stupid. This allows the creation of a swap area larger than the file or partition it resides on.
Also, without this option, mkswap will refuse to erase the first block on a device with a partition table.
-L, --label label
Specify a label for the device, to allow swapon by label.
-p, --pagesize size
Specify the page size (in bytes) to use. This option is usually unnecessary; mkswap reads the size from the kernel.
-U, --uuid UUID
Specify the UUID to use. The default is to generate a UUID.
-v, --swapversion 1
Specify the swap-space version. (This option is currently pointless, as the old -v 0 option has become obsolete and now only -v 1
is supported. The kernel has not supported v0 swap-space format since 2.5.22 (June 2002). The new version v1 is supported since
2.1.117 (August 1998).)
-h, --help
Display help text and exit.
-V, --version
Display version information and exit.
NOTES
The maximum useful size of a swap area depends on the architecture and the kernel version.
The maximum number of the pages that is possible to address by swap area header is 4294967295 (UINT_MAX). The remaining space on the swap
device is ignored.
Presently, Linux allows 32 swap areas. The areas in use can be seen in the file /proc/swaps
mkswap refuses areas smaller than 10 pages.
If you don't know the page size that your machine uses, you may be able to look it up with "cat /proc/cpuinfo" (or you may not - the con-
tents of this file depend on architecture and kernel version).
To set up a swap file, it is necessary to create that file before initializing it with mkswap, e.g. using a command like
# fallocate --length 8GiB swapfile
Note that a swap file must not contain any holes. Using cp(1) to create the file is not acceptable. Neither is use of fallocate(1) on
file systems that support preallocated files, such as XFS or ext4, or on copy-on-write filesystems like btrfs. It is recommended to use
dd(1) and /dev/zero in these cases. Please read notes from swapon(8) before adding a swap file to copy-on-write filesystems.
ENVIRONMENT
LIBBLKID_DEBUG=all
enables libblkid debug output.
SEE ALSO
fdisk(8), swapon(8)
AVAILABILITY
The mkswap command is part of the util-linux package and is available from https://www.kernel.org/pub/linux/utils/util-linux/.
util-linux March 2009 MKSWAP(8)