cvdbset(8) cvdbset(8)
NAME
cvdbset - A program to control cvdb tracing.
SYNOPSIS
cvdbset [options]
DESCRIPTION
cvdbset is a tool for system administrators to control cvdb(8) tracing
information from the Xsan File System client file system.
The level of tracing emitted can be controlled on a per module basis.
The set of modules for which tracing is enabled is called the trace
set. The level of tracing can be refined further by specifying a set of
tracepoints (such as entry/exit points). The set of enabled tracepoints
is called the logmask.
Warning: enabling tracing can have a substantial performance impact.
cvdbset can be used to:
List all the current client modules in the trace set.
Add all modules to the trace set.
Define the trace set.
Add selected modules to trace set
Remove selected modules from the trace set
Set the logmask for a set of modules in the trace set.
Resize the logging buffer
Start/stop continuous tracing
Disable tracing
OPTIONS
no options
Display the whether tracing is enabled/disabled, the size of the
logging buffer, the modules in the trace set, and their corre-
sponding logmasks.
all Enable tracing of all modules. Once cvdbset with a list of mod-
ules is invoked, some modules are turned off. cvdbset all sets
all modules for tracing. When used with + or -, add or remove
all modules.
[:]module1 [:]module2 ...
When invoked with a list of modules, cvdbset first disables all
modules. Then, it enables exactly the given list of modules. To
see all modules that can be enabled, use the cvdbset -l com-
mand/option. If the module name is preceded by a :, all modules
containing the module name will be affected.
+ [:]module1 [:]module2 ...
When invoked with a plus sign (+) as the first argument followed
by a list of modules, the given list of modules is added to the
current trace set. If the module name is preceded by a :, all
modules containing the module name will be affected.
- [:]module1 [:]module2 ...
When invoked with a minus sign (-) as the first argument fol-
lowed by a list of modules, the given list of modules is removed
from the current trace set. If the module name is preceded by a
:, all modules containing the module name will be affected.
-h Display a help message and exit.
-c Enable continuous cvdb tracing. The trace log will be retrieved
once per second and placed in files named cvdbout.000001, ...
-d Disable cvdb tracing.
-g Dump the current trace buffer to standard out.
-l Display whether logging is enabled, the buffer size, and the
logmask for all modules.
-L Display the list of all available tracepoints for use with the
-t option.
-r mb Resize the trace buffer to mb megabytes.
-t tracepoint
For the indicated modules, enable tracing only for the indicated
tracepoints. Multiple -t options can be supplied. Use the -L op-
tion to cvdbset to see a listing of tracepoints.
EXAMPLES
To see what modules are in the trace set and their logmasks, the com-
mand cvdbset with no parameters is used. Here is the output from this
command at start-up.
Debug logging is DISABLED, Bufsize 4194304
Currently set masks:
Module ' proxy_clnt' module 0x0000000000000001 logmask 0xffffffffffffffff
Module ' cvdir' module 0x0000000000000002 logmask 0xffffffffffffffff
Module ' cvdisk' module 0x0000000000000004 logmask 0xffffffffffffffff
Module ' cvnc' module 0x0000000000000008 logmask 0xffffffffffffffff
Module ' cvpath' module 0x0000000000000010 logmask 0xffffffffffffffff
Module ' portmap' module 0x0000000000000020 logmask 0xffffffffffffffff
Module ' cvsock' module 0x0000000000000040 logmask 0xffffffffffffffff
Module ' cvsubr' module 0x0000000000000080 logmask 0xffffffffffffffff
Module ' dmigfs' module 0x0000000000000100 logmask 0xffffffffffffffff
Module ' dmig' module 0x0000000000000200 logmask 0xffffffffffffffff
Module ' dmon' module 0x0000000000000400 logmask 0xffffffffffffffff
Module ' extapi' module 0x0000000000000800 logmask 0xffffffffffffffff
Module ' extent' module 0x0000000000001000 logmask 0xffffffffffffffff
Module ' fsmat' module 0x0000000000002000 logmask 0xffffffffffffffff
Module ' fsmcom' module 0x0000000000004000 logmask 0xffffffffffffffff
Module ' fsmdmig' module 0x0000000000008000 logmask 0xffffffffffffffff
Module ' fsmproxy' module 0x0000000000010000 logmask 0xffffffffffffffff
Module ' fsmrtio' module 0x0000000000020000 logmask 0xffffffffffffffff
Module ' fsmtoken' module 0x0000000000040000 logmask 0xffffffffffffffff
Module ' fsmvfs' module 0x0000000000080000 logmask 0xffffffffffffffff
Module ' fsmvnops' module 0x0000000000100000 logmask 0xffffffffffffffff
Module ' memalloc' module 0x0000000000200000 logmask 0xffffffffffffffff
Module ' proxy_con' module 0x0000000000400000 logmask 0xffffffffffffffff
Module ' quotas' module 0x0000000000800000 logmask 0xffffffffffffffff
Module ' recon' module 0x0000000001000000 logmask 0xffffffffffffffff
Module ' rtio' module 0x0000000002000000 logmask 0xffffffffffffffff
Module ' rwbuf' module 0x0000000004000000 logmask 0xffffffffffffffff
Module ' rwproxy' module 0x0000000008000000 logmask 0xffffffffffffffff
Module ' rwlock' module 0x0000000010000000 logmask 0xffffffffffffffff
Module ' rw' module 0x0000000020000000 logmask 0xffffffffffffffff
Module 'slidingbucket' module 0x0000000040000000 logmask 0xffffffffffffffff
Module ' sockinput' module 0x0000000080000000 logmask 0xffffffffffffffff
Module ' proxy_srv' module 0x0000000100000000 logmask 0xffffffffffffffff
Module ' proxy_subr' module 0x0000000200000000 logmask 0xffffffffffffffff
Module ' vfsops' module 0x0000000400000000 logmask 0xffffffffffffffff
Module ' vnops' module 0x0000000800000000 logmask 0xffffffffffffffff
Module ' perf' module 0x0000001000000000 logmask 0xffffffffffffffff
Module ' md_cvdir' module 0x0000002000000000 logmask 0xffffffffffffffff
Module ' md_cvsock' module 0x0000004000000000 logmask 0xffffffffffffffff
Module ' md_cvsubr' module 0x0000008000000000 logmask 0xffffffffffffffff
Module ' md_dmon' module 0x0000010000000000 logmask 0xffffffffffffffff
Module ' md_fsmcom' module 0x0000020000000000 logmask 0xffffffffffffffff
Module ' md_memalloc' module 0x0000040000000000 logmask 0xffffffffffffffff
Module ' md_rwlock' module 0x0000080000000000 logmask 0xffffffffffffffff
Module ' md_rw' module 0x0000100000000000 logmask 0xffffffffffffffff
Module ' md_rwproxy' module 0x0000200000000000 logmask 0xffffffffffffffff
Module ' md_socksubr' module 0x0000400000000000 logmask 0xffffffffffffffff
Module ' md_vfsops' module 0x0000800000000000 logmask 0xffffffffffffffff
Module ' md_vnops' module 0x0001000000000000 logmask 0xffffffffffffffff
Module ' sh_cvsubr' module 0x0002000000000000 logmask 0xffffffffffffffff
Module ' sh_fsmcom' module 0x0004000000000000 logmask 0xffffffffffffffff
Module ' sh_sockinput' module 0x0008000000000000 logmask 0xffffffffffffffff
Module ' sh_vnops' module 0x0010000000000000 logmask 0xffffffffffffffff
To enable tracing for selected modules:
cvdbset md_vnops rw fsmvnops fsmtoken fsmdmig
This enables tracing for only these five modules and prints the output:
Setting md_vnops.
Setting rw.
Setting fsmvnops.
Setting fsmtoken.
Setting fsmdmig.
cvdb -m modules=0x0001000020148000 logmask=0xffffffffffffffff
If an argument is preceded by a colon (:), then any module whose name
contains the argument as a substring is included.
To enable the md_vnops tracing module and all of the proxy-related mod-
ules:
cvdbset md_vnops :proxy
This displays the following output:
Setting md_vnops.
Setting proxy_clnt.
Setting fsmproxy.
Setting proxy_con.
Setting rwproxy.
Setting proxy_srv.
Setting proxy_subr.
Setting md_rwproxy.
cvdb -m modules=0x0001200308410001 logmask=0xffffffffffffffff
To add rwbuf and vnops modules to the current tracing set with the
cvENTRY and cvEXIT tracepoints enabled:
cvdbset -t cvENTRY -t cvEXIT + rwbuf vnops
This displays the following output:
Adding rwbuf.
Adding vnops.
cvdb -m modules=0x0000000804000000 logmask=0x0000000000000003
To remove rwbuf and vnops from the current tracing set:
cvdbset - rwbuf vnops
This displays the following output:
Clearing rwbuf.
Clearing vnops.
cvdb -m modules=0x0000000804000000 logmask=0x0000000000000000
The special module all can be used with both the + and - options to
add/remove all modules from the trace.
After tracing is enabled, cvdbset -g can be used to retrieve the trace.
When desired, cvdbset -d can be used to disable tracing.
Various cvdb(8) command/options can be used for even finer control of
tracing. See cvdb(8) for more details.
I/O PERFORMANCE ANALYSIS
The 'perf' trace module is very useful to analyze I/O performance, for
example:
cvdbset perf
Then cvdbset -g will display info like this:
PERF: Device Write 41 MB/s IOs 2 exts 1 offs 0x0 len 0x400000 mics 95589 ino 0x5
PERF: VFS Write EofDmaAlgn 41 MB/s offs 0x0 len 0x400000 mics 95618 ino 0x5
The 'PERF: Device' trace shows throughput measured for the device I/O.
It also shows the number of I/O's that it was broken into and number of
extents (sequence of consecutive filesystem blocks).
The 'PERF: VFS' trace shows throughput measured for the read or write
system call and significant aspects of the I/O including:
Dma - DMA
Buf - Buffered
Eof - File extended
Algn - Well formed DMA I/O
Shr - File is shared by another client
Rt - File is real time
Zr - Hole in file was zeroed
Both traces also report file offset, I/O size, latency (mics), and in-
ode number.
Sample use cases:
1) Verify I/O properties are as expected.
The VFS trace can be used to ensure that the displayed properties
are consistent with expectations, for example, well formed, buffered
vs. DMA, shared/non-shared, or I/O size. If a small I/O is being
performed DMA then performance will be poor. If DMA I/O is not well
formed then it requires an extra data copy and may even be broken
into small chunks. Zeroing holes in files has a performance impact.
2) Determine if metadata operations are impacting performance.
If VFS throughput is inconsistent or significantly less than Device
throughput then it may be caused by metadata operations. In that
case it would be useful to display 'fsmtoken', 'fsmvnops', and 'fs-
mdmig' traces in addition to 'perf'.
3) Identify disk performance issues.
If Device throughput is inconsistent or less than expected then it
may indicate a slow disk in a storage pool or that RAID tuning is
necessary.
4) Identify file fragmentation.
If the extent count 'exts' is high then it may indicate a fragmenta-
tion problem. This causes the device I/O's to broken into smaller
chunks which can significantly impact throughput.
5) Identify read/modify/write condition.
If buffered VFS writes are causing Device reads then it may be bene-
ficial to match I/O request size to a multiple of the 'cachebufsize'
(default 64KB, see mount_acfs(8)). Another way to avoid this is by
truncating the file before writing.
SEE ALSO
cvdb(8)
Xsan File System June 2014 cvdbset(8)
Mac OS X 10.12.3 - Generated Thu Feb 9 18:12:42 CST 2017