| Table of Contents |
|---|
Kernel
Swap
My 48GB swap file system
...
isn't
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fully
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recognized.
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Q.
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What
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is
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the
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max
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amount
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of
...
swap
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a
...
system
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can
...
use?
...
A.
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Are
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you
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sure
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you
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want/need
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that
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much
...
swap
...
anyway?
...
The
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old-school
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2-4x
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RAM
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doesn't
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really
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apply,
...
though
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you
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may
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want
...
a
...
bit
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more
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than
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1x
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physical
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RAM
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if
...
you
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are
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capturing
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a
...
crash
...
dump,
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and
...
some
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systems
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have
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>32GB
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RAM
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now.
...
Swap
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can
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be
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limited
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by
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kern.maxswzone
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which
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controls
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the
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size
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of
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metadata
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use
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to
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track
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swap
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(8.X
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default
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is
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64MB
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allowing
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~15GB
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of
...
swap).
...
Note
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other
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changes
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are
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required
...
to
...
...
...
...
Q. What is this error: "swap zone exhausted, increase kern.maxswzone" if I didn't run out of swap?
A. kern.maxswzone is a kern var (configurable via loader.conf) which allocates memory virtual memory for storing metadata about swap. Default is something like 64 MB which allows around 14GB of swap to be utilized (http://lists.freebsd.org/pipermail/freebsd-stable/2007-May/
...
034926.html). Default in 7.X is 32 MB. Further discussion http://lists.freebsd.org/pipermail/freebsd-hackers/2009-October/029616.html or http://blog.frankleonhardt.com/2011/large-swap-files-on-freebsd-die-with-mystery-killed-howto-add-lots-of-swap-space/. To check on how much of your SWAPMETA is used:
| Code Block |
|---|
[mane:~]# vmstat -z | perl -ne '$.==1&&print;/SWAPMETA/&&print'
ITEM SIZE LIMIT USED FREE REQUESTS FAILURES
SWAPMETA: 288, 116519, 0, 0, 0, 0 |
What is the best way to configure a swap backed /tmp?
Q. I want to use swap backed /tmp, but I understand it can be configured in multiple ways, including in /etc/fstab and the /etc/rc.*
...
scripts.
...
What
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is
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the
...
best
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way
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to
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set
...
this
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up?
...
A.
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Discussions
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here:
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http://forums.freebsd.org/showthread.php?t=3335,
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http://forums.freebsd.org/showthread.php?t=1561.
...
Setting
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up
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from
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/etc/fstab:
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"md
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/tmp
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mfs
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rw,-s14336m,-oasync,-onoatime,-S,-Otime
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0
...
0"
...
(size,
...
async,
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don't
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update
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access
...
time,
...
no
...
soft
...
updates,
...
optimize
...
for
...
speed).
...
Remember,
...
you
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don't
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really
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want
...
your
...
system
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to
...
swap,
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if
...
it
...
does,
...
obviously,
...
memory
...
access
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slows
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to
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disk
...
I/O
...
speed.
...
Via rc.conf:
| Code Block |
|---|
fstab: {code} tmpmfs="YES" # Set to YES to always create an mfs /tmp, NO to never tmpsize="5g" # Size of mfs /tmp if created tmpmfs_flags="-S -o async,noexec" # Extra mdmfs options for the mfs /tmp, -S no softupdates {code} Q. What is this error: "swap zone exhausted, increase kern.maxswzone" if I didn't run out of swap? A. kern.maxswzone is a kern var (configurable via loader.conf) which allocates memory virtual memory for storing metadata about swap. Default is something like 64 MB which allows around 14GB of swap to be utilized (http://lists.freebsd.org/pipermail/freebsd-stable/2007-May/034926.html). [Default in 7.X was 32 MB|http://freebsd.1045724.n5.nabble.com/Kernel-swap-zone-exhausted-what-is-the-max-allowed-FBSD-7-2-td3782914.html]. h1. File Systems h2. Gjournaling h3. Are these log messages problems? "fsync: giving up on dirty" and "Cannot suspend file system"? Q. These error messages show up frequently in messages: "fsync: giving up on dirty" and "GEOM_JOURNAL: Cannot suspend file system |
File Systems
Gjournaling
Are these log messages problems? "fsync: giving up on dirty" and "Cannot suspend file system"?
Q. These error messages show up frequently in messages: "fsync: giving up on dirty" and "GEOM_JOURNAL: Cannot suspend file system /xx/yy".
...
Is
...
this
...
a
...
problem?
...
Is
...
my
...
journal
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having
...
issues?
...
A.
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These
...
messages
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are
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safe
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to
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ignore.
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http://www.mail-archive.com/[email protected]/msg196977.html
...
Seems
...
to
...
be
...
a
...
harmless
...
message
...
that
...
occurs
...
under
...
certain
...
load
...
conditions
...
and
...
indicates
...
that
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a
...
journal
...
switch
...
is
...
pending.
