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Resource management tools help you monitor performance and identify
performance issues. There are many ways to collect the system data
you need to investigate performance problems.
The Linux kernel 2.4 version of the device driver for FCP provides some basic statistics
of the I/O traffic pattern for SCSI devices for Linux on System z.
For Novell/SUSE kernel version 2.4.21-251 and higher the device driver gathers independent
statistics for each FCP subchannel. Statistics are turned off by default and
may be activated as described below.
Earlier versions of the device driver offer statistics data as a summation
of corresponding requests across all FCP subchannels. It is all times active.
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Statistics are turned off by default to allow maximum performance. Gathering
statistical data decreases performance by about 2 percent. Enabling, disabling
and resetting statistics can be achieved by using the following commands defined
for the /proc file system interface from the device driver for
FCP. Make sure to choose the correct /proc file system entry as
indicated below.
- Enable (turn data gathering on):
echo stat on > /proc/scsi/zfcp/devno0x????/status
- Disable (turn data gathering off and discard all statistical data collected
so far):
echo stat off > /proc/scsi/zfcp/devno0x????/status
- Reset (either turn data gathering on, if disabled, or discard all statistical
data collected so far without turning statistics off):
echo stat reset > /proc/scsi/zfcp/devno0x????/status
where devno0x???? is the FCP device address.
Note: To use this interface, make sure that you have configured the
corresponding FCP device in the zfcp device driver in /proc/scsi/zfcp/map.
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The statistical data are provided at the end of the file
/proc/scsi/zfcp/devno0x????/status for Novell/SUSE kernel version
2.4.21-251 and higher
(the same HBA's /proc file system entry that you have used to
enable statistics)./proc/scsi/zfcp/mod_parm for earlier versions
The format of an entry is:
<tag> <value>:<occurrence>
where
<tag> ::= rr | wr
rr is a read request
wr is a write request
<value> is a 32 bit unsigned integer indicating a particular
request size (printed in hexadecimal with padded zeros)
<occurrence> is a 32 bit unsigned integer indicating the
number of requests of that size (printed in hexadecimal with padded zeros)
Usually the statistical data comprise a list of several entries, depending
on the actual traffic pattern.
The list of entries is sorted by tag and occurrence.
Example:
rr 0x0000a800:0x00000007
is 7 read requests of 42 KB each
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It is very unlikely that FCP needs to omit portions of the statistical
data due to resource constraints. Check the field "missed
stats" in /proc/scsi/zfcp/devno0x????/status
for the number of requests that could not be collected during
the gathering of statistical data. It is recommended to make
sure that the number of misses is very low, preferably zero,
when FCP statistics are evaluated.
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If you download any software from this web site please be
aware of the Warranty
Disclaimer and Limitation of Liability.
These sample tools assist you to handle the FCP statistics:
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shows
- the name of the files parsed for statistic data
- the number of requests
- the number of requests where portions of the statistical data are
omitted (missed stats)
- the number of requests which were delayed because the FCP subchannel's
queues were full
- the distribution of request sizes
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Download
fcpstats.tar.gz
MD5
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| Additional scripts for easier handling: |
These scripts are for Linux version 2.4.21-251 and higher.
They are working on all devices found under /proc/scsi/zfcp/devno0x???? |
| fcpstats_on.sh |
switches statistics for all FCP subchannels on
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| fcpstats_off.sh |
switches statistics for all FCP subchannels off
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| fcpstats_evaluate.sh |
shows statistics data from all FCP subchannels
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- After download and extraction, perform the following command to make the
tools executable for the Linux shell:
chmod u+x fcpstats_on.sh fcpstats_off.sh fcpstats_evaluate.sh fcpstats.pl
- You can use the scripts as templates to adapt them to your specific needs.
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Usage
./fcpstats.pl <file containing FCP statistics data> [<file containing
FCP statistics data>]
For releases prior to 2.4.21-251: The statistics are available in /proc/scsi/zfcp/mod_parm
For release 2.4.21-251 and higher: The statistics are available in /proc/scsi/zfcp/devno0x????//status
Note: Every time FCP's statistics are read from the respective /proc
file system file a new and current snapshot of data
is produced. Depending on your needs it might be beneficial
to create permanent copies of statistics snapshots by
copying respective /proc file system files
to a safe location, and to use the parser for off-line
evaluation.
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This is a sample output from a system with 4 FCP subchannels under a database
workload on an ext2 file system. It shows the typical pattern of many 4KB requests,
which corresponds to the page size used by the database. In this example, larger
write requests occur as well since Linux might be able to merge cached buffers
into an aggregated I/O request on their way out to a target device.
Other request sizes might be caused by the fact that the zfcp driver accounts
any type of outbound or inbound I/O buffer, not only those associated with reading
or writing data to disk. There are also other SCSI commands, like for communication
between FCP adapter and disk devices. These requests are few and far between,
and usually occur in the context of device detection or error recovery.
parsing /proc/scsi/zfcp/devno0x1706/status
parsing /proc/scsi/zfcp/devno0x1786/status
parsing /proc/scsi/zfcp/devno0x1806/status
parsing /proc/scsi/zfcp/devno0x50ee/status
| device |
devno0x1706/status |
devno0x1786/status |
devno0x1806/status |
devno0x50ee/status |
| requests |
6858406
|
6822876
|
6819385
|
6858359
|
| missed stats |
0
|
0
|
0
|
0
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| queue full |
15063
|
8071
|
12296
|
7007
|
| Size[KB] |
Write |
Read |
Write |
Read |
Write |
Read |
Write |
Read |
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
1
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
2
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
3
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
4
|
1092678
|
5047642
|
1094364
|
5051776
|
1091385
|
5043192
|
1091047
|
5044008
|
|
5
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
6
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
7
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
8
|
11686
|
3
|
11646
|
2
|
11577
|
2
|
11526
|
4
|
|
9
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
10
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
11
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
12
|
31687
|
3
|
31601
|
3
|
31749
|
3
|
31747
|
3
|
|
13
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
14
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
15
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
16
|
3474
|
0
|
3410
|
0
|
3424
|
0
|
3491
|
0
|
|
17
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
18
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
19
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
20
|
24326
|
0
|
24503
|
0
|
24316
|
0
|
24398
|
0
|
|
21
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
22
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
23
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
24
|
199
|
0
|
224
|
0
|
216
|
0
|
226
|
0
|
|
25
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
26
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
27
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
28
|
189
|
0
|
185
|
0
|
203
|
0
|
167
|
0
|
|
29
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
30
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
31
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
32
|
1102
|
0
|
1058
|
0
|
1031
|
0
|
1031
|
0
|
|
33
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
34
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
35
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
36
|
0
|
0
|
0
|
0
|
1
|
0
|
0
|
0
|
|
37
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
38
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
39
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
40
|
1
|
0
|
0
|
1
|
2
|
0
|
0
|
1
|
|
41
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
42
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
43
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
44
|
0
|
0
|
2
|
0
|
1
|
0
|
1
|
0
|
|
45
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
46
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
47
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
48
|
0
|
0
|
1
|
0
|
0
|
0
|
1
|
0
|
|
|
|
|
|
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