26. Command Line Utilities¶
Several command line utilities which are provided with FreeNAS® are demonstrated in this section.
The following utilities can be used for benchmarking and performance testing:
- Iperf: used for measuring maximum TCP and UDP bandwidth performance
- Netperf: a tool for measuring network performance
- IOzone: filesystem benchmark utility used to perform a broad filesystem analysis
- arcstat: used to gather ZFS ARC statistics
The following utilities are specific to RAID controllers:
- tw_cli:_used to monitor and maintain 3ware RAID controllers
- MegaCli: used to configure and manage Broadcom MegaRAID SAS family of RAID controllers
This section also describes these utilities:
- freenas-debug: the backend used to dump FreeNAS® debugging information
- tmux: a terminal multiplexer similar to GNU screen
- Dmidecode: reports information about system hardware as described in the system’s BIOS
26.1. Iperf¶
Iperf is a utility for measuring maximum TCP and UDP bandwidth performance. It can be used to chart network throughput over time. For example, it is used to test the speed of different types of shares to determine which type performs best on the network.
FreeNAS® includes the iperf server. To perform network testing, install an iperf client on a desktop system that has network access to the FreeNAS® system. This section demonstrates how to use the xjperf user interface client as it works on Windows, macOS, Linux, and BSD systems.
Since this client is Java-based, the appropriate JRE must be installed on the client computer.
Linux and BSD users will need to install the iperf package using the package management system for their operating system.
To start xjperf on Windows: unzip the downloaded file, start Command Prompt in Run as administrator mode, cd to the unzipped folder, and run jperf.bat.
To start xjperf on macOS, Linux, or BSD, unzip the downloaded file, cd to the unzipped directory, type chmod u+x jperf.sh, and run ./jperf.sh.
Start the iperf server on FreeNAS® when the client is ready.
Note
Beginning with FreeNAS® version 11.1, both iperf2 and iperf3 are pre-installed. To use iperf2, use iperf. To use iperf3, instead type iperf3. The examples below are for iperf2.
To see the available server options, open Shell and type:
iperf --help | more
or:
iperf3 --help | more
For example, to perform a TCP test and start the server in daemon mode (to get the prompt back), type:
iperf -sD
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 64.0 KByte (default)
------------------------------------------------------------
Running Iperf Server as a daemon
The Iperf daemon process ID: 4842
Note
The daemon process stops when Shell closes. Set up the environment with shares configured and started before starting the Iperf process.
From the desktop, open the client. Enter the IP of address of the FreeNAS® system, specify the running time for the test under (the default test time is 10 seconds), and click the Run Iperf! button. Figure 26.1.1 shows an example of the client running on a Windows system while an SFTP transfer is occurring on the network.
Fig. 26.1.1 Viewing Bandwidth Statistics Using xjperf
Check the type of traffic before testing UPD or TCP. The iperf server is used to get additional details for services using TCP iperf -sD or UDP iperf -sDu. The startup message indicates when the server is listening for TCP or UDP. The sockstat -4 | more command gives an overview of the services running on the FreeNAS® system. This helps to determine if the traffic to test is UDP or TCP.
sockstat -4 | more
USER COMMAND PID FD PROTO LOCAL ADDRESS FOREIGN ADDRESS
root iperf 4870 6 udp4 *:5001 *:*
root iperf 4842 6 tcp4 *:5001 *:*
www nginx 4827 3 tcp4 127.0.0.1:15956 127.0.0.1:9042
www nginx 4827 5 tcp4 192.168.2.11:80 192.168.2.26:56964
www nginx 4827 7 tcp4 *:80 *:*
root sshd 3852 5 tcp4 *:22 *:*
root python 2503 5 udp4 *:* *:*
root mountd 2363 7 udp4 *:812 *:*
root mountd 2363 8 tcp4 *:812 *:*
root rpcbind 2359 9 udp4 *:111 *:*
root rpcbind 2359 10 udp4 *:886 *:*
root rpcbind 2359 11 tcp4 *:111 *:*
root nginx 2044 7 tcp4 *:80 *:*
root python 2029 3 udp4 *:* *:*
root python 2029 4 tcp4 127.0.0.1:9042 *:*
root python 2029 7 tcp4 127.0.0.1:9042 127.0.0.1:15956
root ntpd 1548 20 udp4 *:123 *:*
root ntpd 1548 22 udp4 192.168.2.11:123*:*
root ntpd 1548 25 udp4 127.0.0.1:123 *:*
root syslogd 1089 6 udp4 127.0.0.1:514 *:*
When testing is finished, either type killall iperf or close Shell to terminate the iperf server process.
26.2. Netperf¶
Netperf is a benchmarking utility that can be used to measure the performance of unidirectional throughput and end-to-end latency.
Before using the netperf command, start its server process with this command:
netserver
Starting netserver with host 'IN(6)ADDR_ANY' port '12865' and family AF_UNSPEC
The following command displays the available options for performing tests with the netperf command. The Netperf Manual describes each option in more detail and explains how to perform many types of tests. It is the best reference for understanding how each test works and how to interpret the results. When testing is finished, type killall netserver to stop the server process.
netperf -h |more
Usage: netperf [global options] -- [test options]
Global options:
-a send,recv Set the local send,recv buffer alignment
-A send,recv Set the remote send,recv buffer alignment
-B brandstr Specify a string to be emitted with brief output
-c [cpu_rate] Report local CPU usage
-C [cpu_rate] Report remote CPU usage
-d Increase debugging output
-D [secs,units] * Display interim results at least every secs seconds
using units as the initial guess for units per second
-f G|M|K|g|m|k Set the output units
-F fill_file Pre-fill buffers with data from fill_file
-h Display this text
-H name|ip,fam * Specify the target machine and/or local ip and family
-i max,min Specify the max and min number of iterations (15,1)
-I lvl[,intvl] Specify confidence level (95 or 99) (99)
and confidence interval in percentage (10)
-j Keep additional timing statistics
-l testlen Specify test duration (>0 secs) (<0 bytes|trans)
-L name|ip,fam * Specify the local ip|name and address family
-o send,recv Set the local send,recv buffer offsets
-O send,recv Set the remote send,recv buffer offset
-n numcpu Set the number of processors for CPU util
-N Establish no control connection, do 'send' side only
-p port,lport* Specify netserver port number and/or local port
-P 0|1 Don't/Do display test headers
-r Allow confidence to be hit on result only
-s seconds Wait seconds between test setup and test start
-S Set SO_KEEPALIVE on the data connection
-t testname Specify test to perform
-T lcpu,rcpu Request netperf/netserver be bound to local/remote cpu
-v verbosity Specify the verbosity level
-W send,recv Set the number of send,recv buffers
-v level Set the verbosity level (default 1, min 0)
-V Display the netperf version and exit
For those options taking two parms, at least one must be specified. Specifying one value without a comma will set both parms to that value, specifying a value with a leading comma will set just the second parm, and specifying a value with a trailing comma will set the first. To set each parm to unique values, specify both and separate them with a comma.
For these options taking two parms, specifying one value with no comma will only set the first parms and will leave the second at the default value. To set the second value it must be preceded with a comma or be a comma-separated pair. This is to retain previous netperf behavior.
26.3. IOzone¶
IOzone is a disk and filesystem benchmarking tool. It can be used to test file I/O performance for the following operations: read, write, re-read, re-write, read backwards, read strided, fread, fwrite, random read, pread, mmap, aio_read, and aio_write.
FreeNAS® ships with IOzone so it can be run from Shell. When using IOzone on FreeNAS®, cd to a directory in a pool that you have permission to write to, otherwise an error about being unable to write the temporary file will occur.
Before using IOzone, read through the IOzone documentation PDF as it describes the tests, the many command line switches, and how to interpret the results.
These resources provide good starting points on which tests to run, when to run them, and how to interpret the results:
- How To Measure Linux Filesystem I/O Performance With iozone
- Analyzing NFS Client Performance with IOzone
- 10 iozone Examples for Disk I/O Performance Measurement on Linux
Type the following command to receive a summary of the available switches. IOzone is comprehensive so it may take some time to learn how to use the tests effectively.
Starting with version 9.2.1, FreeNAS® enables compression on newly
created ZFS pools by default. Since IOzone creates test data that is
compressible, this can skew test results. To configure IOzone to
generate incompressible test data, include the options
-+w 1 -+y 1 -+C 1.
Alternatively, consider temporarily disabling compression on the ZFS pool or dataset when running IOzone benchmarks.
Note
If a visual representation of the collected data is preferred, scripts are available to render IOzone’s output in Gnuplot.
iozone -h | more
iozone: help mode
Usage: iozone[-s filesize_Kb] [-r record_size_Kb] [-f [path]filename] [-h]
[-i test] [-E] [-p] [-a] [-A] [-z] [-Z] [-m] [-M] [-t children]
[-l min_number_procs] [-u max_number_procs] [-v] [-R] [-x] [-o]
[-d microseconds] [-F path1 path2...] [-V pattern] [-j stride]
[-T] [-C] [-B] [-D] [-G] [-I] [-H depth] [-k depth] [-U mount_point]
[-S cache_size] [-O] [-L cacheline_size] [-K] [-g maxfilesize_Kb]
[-n minfilesize_Kb] [-N] [-Q] [-P start_cpu] [-e] [-c] [-b Excel.xls]
[-J milliseconds] [-X write_telemetry_filename] [-w] [-W]
[-Y read_telemetry_filename] [-y minrecsize_Kb] [-q maxrecsize_Kb]
[-+u] [-+m cluster_filename] [-+d] [-+x multiplier] [-+p # ]
[-+r] [-+t] [-+X] [-+Z] [-+w percent dedupable] [-+y percent_interior_dedup]
[-+C percent_dedup_within]
-a Auto mode
-A Auto2 mode
-b Filename Create Excel worksheet file
-B Use mmap() files
-c Include close in the timing calculations
-C Show bytes transferred by each child in throughput testing
-d # Microsecond delay out of barrier
-D Use msync(MS_ASYNC) on mmap files
-e Include flush (fsync,fflush) in the timing calculations
-E Run extension tests
-f filename to use
-F filenames for each process/thread in throughput test
-g # Set maximum file size (in Kbytes) for auto mode (or #m or #g)
-G Use msync(MS_SYNC) on mmap files
-h help
-H # Use POSIX async I/O with # async operations
-i # Test to run (0=write/rewrite, 1=read/re-read, 2=random-read/write
3=Read-backwards, 4=Re-write-record, 5=stride-read, 6=fwrite/re-fwrite
7=fread/Re-fread, 8=random_mix, 9=pwrite/Re-pwrite, 10=pread/Re-pread
11=pwritev/Re-pwritev, 12=preadv/Re-preadv)
-I Use VxFS VX_DIRECT, O_DIRECT,or O_DIRECTIO for all file operations
-j # Set stride of file accesses to (# * record size)
-J # milliseconds of compute cycle before each I/O operation
-k # Use POSIX async I/O (no bcopy) with # async operations
-K Create jitter in the access pattern for readers
-l # Lower limit on number of processes to run
-L # Set processor cache line size to value (in bytes)
-m Use multiple buffers
-M Report uname -a output
-n # Set minimum file size (in Kbytes) for auto mode (or #m or #g)
-N Report results in microseconds per operation
-o Writes are synch (O_SYNC)
-O Give results in ops/sec.
-p Purge on
-P # Bind processes/threads to processors, starting with this cpu
-q # Set maximum record size (in Kbytes) for auto mode (or #m or #g)
-Q Create offset/latency files
-r # record size in Kb
or -r #k .. size in Kb
or -r #m .. size in Mb
or -r #g .. size in Gb
-R Generate Excel report
-s # file size in Kb
or -s #k .. size in Kb
or -s #m .. size in Mb
or -s #g .. size in Gb
-S # Set processor cache size to value (in Kbytes)
-t # Number of threads or processes to use in throughput test
-T Use POSIX pthreads for throughput tests
-u # Upper limit on number of processes to run
-U Mount point to remount between tests
-v version information
-V # Verify data pattern write/read
-w Do not unlink temporary file
-W Lock file when reading or writing
-x Turn off stone-walling
-X filename Write telemetry file. Contains lines with (offset reclen compute_time) in ascii
-y # Set minimum record size (in Kbytes) for auto mode (or #m or #g)
-Y filename Read telemetry file. Contains lines with (offset reclen compute_time) in ascii
-z Used in conjunction with -a to test all possible record sizes
-Z Enable mixing of mmap I/O and file I/O
-+E Use existing non-Iozone file for read-only testing
-+K Sony special. Manual control of test 8.
-+m Cluster_filename Enable Cluster testing
-+d File I/O diagnostic mode. (To troubleshoot a broken file I/O subsystem)
-+u Enable CPU utilization output (Experimental)
-+x # Multiplier to use for incrementing file and record sizes
-+p # Percentage of mix to be reads
-+r Enable O_RSYNC|O_SYNC for all testing.
-+t Enable network performance test. Requires -+m
-+n No retests selected.
-+k Use constant aggregate data set size.
-+q Delay in seconds between tests.
-+l Enable record locking mode.
-+L Enable record locking mode, with shared file.
-+B Sequential mixed workload.
-+A # Enable madvise. 0 = normal, 1=random, 2=sequential 3=dontneed, 4=willneed
-+N Do not truncate existing files on sequential writes.
-+S # Dedup-able data is limited to sharing within each numerically identified file set
-+V Enable shared file. No locking.
-+X Enable short circuit mode for filesystem testing ONLY
ALL Results are NOT valid in this mode.
-+Z Enable old data set compatibility mode. WARNING.. Published
hacks may invalidate these results and generate bogus, high values for results.
-+w ## Percent of dedup-able data in buffers.
-+y ## Percent of dedup-able within & across files in buffers.
-+C ## Percent of dedup-able within & not across files in buffers.
-+H Hostname Hostname of the PIT server.
-+P Service Service of the PIT server.
-+z Enable latency histogram logging.
26.4. arcstat¶
Arcstat is a script that prints out ZFS ARC statistics. Originally it was a perl script created by Sun. That perl script was ported to FreeBSD and then ported as a Python script for use on FreeNAS®.
Watching ARC hits/misses and percentages shows how well the ZFS pool is fetching from the ARC rather than using disk I/O. Ideally, there will be as many things fetching from cache as possible. Keep the load in mind while reviewing the stats. For random reads, expect a miss and having to go to disk to fetch the data. For cached reads, expect it to pull out of the cache and have a hit.
Like all cache systems, the ARC takes time to fill with data. This means that it will have a lot of misses until the pool has been in use for a while. If there continues to be lots of misses and high disk I/O on cached reads, there is cause to investigate further and tune the system.
The FreeBSD ZFS Tuning Guide provides some suggestions for commonly tuned sysctl values. It should be noted that performance tuning is more of an art than a science and that any changes made will probably require several iterations of tune and test. Be aware that what needs to be tuned will vary depending upon the type of workload and that what works for one one network may not benefit another.
In particular, the value of pre-fetching depends upon the amount of memory and the type of workload, as seen in Understanding ZFS: Prefetch
FreeNAS® provides two command line scripts which can be manually run from Shell:
- arc_summary.py: provides a summary of the statistics
- arcstat.py: used to watch the statistics in real time
The advantage of these scripts is that they provide real time information, whereas the current web interface reporting mechanism is designed to only provide graphs charted over time.
This forum post demonstrates some examples of using these scripts with hints on how to interpret the results.
To view the help for arcstat.py:
arcstat.py -h
[-havxp] [-f fields] [-o file] [-s string] [interval [count]]
-h : Print this help message
-a : Print all possible stats
-v : List all possible field headers and definitions
-x : Print extended stats
-f : Specify specific fields to print (see -v)
-o : Redirect output to the specified file
-s : Override default field separator with custom character or string
-p : Disable auto-scaling of numerical fields
Examples:
arcstat -o /tmp/a.log 2 10
arcstat -s "," -o /tmp/a.log 2 10
arcstat -v
arcstat -f time,hit%,dh%,ph%,mh% 1
To view ARC statistics in real time, specify an interval and a count. This command will display every 1 second for a count of five.
arcstat.py 1 5
time read miss miss% dmis dm% pmis pm% mmis mm% arcsz c
06:19:03 7 0 0 0 0 0 0 0 0 153M 6.6G
06:19:04 257 0 0 0 0 0 0 0 0 153M 6.6G
06:19:05 193 0 0 0 0 0 0 0 0 153M 6.6G
06:19:06 193 0 0 0 0 0 0 0 0 153M 6.6G
06:19:07 255 0 0 0 0 0 0 0 0 153M 6.6G
Table 26.4.1 briefly describes the columns in the output.
| Column | Description |
|---|---|
| read | total ARC accesses/second |
| miss | ARC misses/second |
| miss% | ARC miss percentage |
| dmis | demand data misses/second |
| dm% | demand data miss percentage |
| pmis | prefetch misses per second |
| pm% | prefetch miss percentage |
| mmis | metadata misses/second |
| mm% | metadata miss percentage |
| arcsz | arc size |
| c | arc target size |
To receive a summary of statistics, use:
arcsummary.py
System Memory:
2.36% 93.40 MiB Active, 8.95% 353.43 MiB Inact
8.38% 330.89 MiB Wired, 0.15% 5.90 MiB Cache
80.16% 3.09 GiB Free, 0.00% 0 Bytes Gap
Real Installed: 4.00 GiB
Real Available: 99.31% 3.97 GiB
Real Managed: 97.10% 3.86 GiB
Logical Total: 4.00 GiB
Logical Used: 13.93% 570.77 MiB
Logical Free: 86.07% 3.44 GiB
Kernel Memory: 87.62 MiB
Data: 69.91% 61.25 MiB
Text: 30.09% 26.37 MiB
Kernel Memory Map: 3.86 GiB
Size: 5.11% 201.70 MiB
Free: 94.89% 3.66 GiB
ARC Summary: (HEALTHY)
Storage pool Version: 5000
Filesystem Version: 5
Memory Throttle Count: 0
ARC Misc:
Deleted: 8
Mutex Misses: 0
Evict Skips: 0
ARC Size: 5.83% 170.45 MiB
Target Size: (Adaptive) 100.00% 2.86 GiB
Min Size (Hard Limit): 12.50% 365.69 MiB
Max Size (High Water): 8:1 2.86 GiB
ARC Size Breakdown:
Recently Used Cache Size: 50.00% 1.43 GiB
Frequently Used Cache Size: 50.00% 1.43 GiB
ARC Hash Breakdown:
Elements Max: 5.90k
Elements Current: 100.00% 5.90k
Collisions: 72
Chain Max: 1
Chains: 23
ARC Total accesses: 954.06k
Cache Hit Ratio: 99.18% 946.25k
Cache Miss Ratio: 0.82% 7.81k
Actual Hit Ratio: 98.84% 943.00k
Data Demand Efficiency: 99.20% 458.77k
CACHE HITS BY CACHE LIST:
Anonymously Used: 0.34% 3.25k
Most Recently Used: 3.73% 35.33k
Most Frequently Used: 95.92% 907.67k
Most Recently Used Ghost: 0.00% 0
Most Frequently Used Ghost: 0.00% 0
CACHE HITS BY DATA TYPE:
Demand Data: 48.10% 455.10k
Prefetch Data: 0.00% 0
Demand Metadata: 51.56% 487.90k
Prefetch Metadata: 0.34% 3.25k
CACHE MISSES BY DATA TYPE:
Demand Data: 46.93% 3.66k
Prefetch Data: 0.00% 0
Demand Metadata: 49.76% 3.88k
Prefetch Metadata: 3.30% 258
ZFS Tunable (sysctl):
kern.maxusers 590
vm.kmem_size 4141375488
vm.kmem_size_scale 1
vm.kmem_size_min 0
vm.kmem_size_max 1319413950874
vfs.zfs.vol.unmap_enabled 1
vfs.zfs.vol.mode 2
vfs.zfs.sync_pass_rewrite 2
vfs.zfs.sync_pass_dont_compress 5
vfs.zfs.sync_pass_deferred_free 2
vfs.zfs.zio.exclude_metadata 0
vfs.zfs.zio.use_uma 1
vfs.zfs.cache_flush_disable 0
vfs.zfs.zil_replay_disable 0
vfs.zfs.version.zpl 5
vfs.zfs.version.spa 5000
vfs.zfs.version.acl 1
vfs.zfs.version.ioctl 5
vfs.zfs.debug 0
vfs.zfs.super_owner 0
vfs.zfs.min_auto_ashift 9
vfs.zfs.max_auto_ashift 13
vfs.zfs.vdev.write_gap_limit 4096
vfs.zfs.vdev.read_gap_limit 32768
vfs.zfs.vdev.aggregation_limit 131072
vfs.zfs.vdev.trim_max_active 64
vfs.zfs.vdev.trim_min_active 1
vfs.zfs.vdev.scrub_max_active 2
vfs.zfs.vdev.scrub_min_active 1
vfs.zfs.vdev.async_write_max_active 10
vfs.zfs.vdev.async_write_min_active 1
vfs.zfs.vdev.async_read_max_active 3
vfs.zfs.vdev.async_read_min_active 1
vfs.zfs.vdev.sync_write_max_active 10
vfs.zfs.vdev.sync_write_min_active 10
vfs.zfs.vdev.sync_read_max_active 10
vfs.zfs.vdev.sync_read_min_active 10
vfs.zfs.vdev.max_active 1000
vfs.zfs.vdev.async_write_active_max_dirty_percent60
vfs.zfs.vdev.async_write_active_min_dirty_percent30
vfs.zfs.vdev.mirror.non_rotating_seek_inc1
vfs.zfs.vdev.mirror.non_rotating_inc 0
vfs.zfs.vdev.mirror.rotating_seek_offset1048576
vfs.zfs.vdev.mirror.rotating_seek_inc 5
vfs.zfs.vdev.mirror.rotating_inc 0
vfs.zfs.vdev.trim_on_init 1
vfs.zfs.vdev.larger_ashift_minimal 0
vfs.zfs.vdev.bio_delete_disable 0
vfs.zfs.vdev.bio_flush_disable 0
vfs.zfs.vdev.cache.bshift 16
vfs.zfs.vdev.cache.size 0
vfs.zfs.vdev.cache.max 16384
vfs.zfs.vdev.metaslabs_per_vdev 200
vfs.zfs.vdev.trim_max_pending 10000
vfs.zfs.txg.timeout 5
vfs.zfs.trim.enabled 1
vfs.zfs.trim.max_interval 1
vfs.zfs.trim.timeout 30
vfs.zfs.trim.txg_delay 32
vfs.zfs.space_map_blksz 4096
vfs.zfs.spa_slop_shift 5
vfs.zfs.spa_asize_inflation 24
vfs.zfs.deadman_enabled 1
vfs.zfs.deadman_checktime_ms 5000
vfs.zfs.deadman_synctime_ms 1000000
vfs.zfs.recover 0
vfs.zfs.spa_load_verify_data 1
vfs.zfs.spa_load_verify_metadata 1
vfs.zfs.spa_load_verify_maxinflight 10000
vfs.zfs.check_hostid 1
vfs.zfs.mg_fragmentation_threshold 85
vfs.zfs.mg_noalloc_threshold 0
vfs.zfs.condense_pct 200
vfs.zfs.metaslab.bias_enabled 1
vfs.zfs.metaslab.lba_weighting_enabled 1
vfs.zfs.metaslab.fragmentation_factor_enabled1
vfs.zfs.metaslab.preload_enabled 1
vfs.zfs.metaslab.preload_limit 3
vfs.zfs.metaslab.unload_delay 8
vfs.zfs.metaslab.load_pct 50
vfs.zfs.metaslab.min_alloc_size 33554432
vfs.zfs.metaslab.df_free_pct 4
vfs.zfs.metaslab.df_alloc_threshold 131072
vfs.zfs.metaslab.debug_unload 0
vfs.zfs.metaslab.debug_load 0
vfs.zfs.metaslab.fragmentation_threshold70
vfs.zfs.metaslab.gang_bang 16777217
vfs.zfs.free_bpobj_enabled 1
vfs.zfs.free_max_blocks 18446744073709551615
vfs.zfs.no_scrub_prefetch 0
vfs.zfs.no_scrub_io 0
vfs.zfs.resilver_min_time_ms 3000
vfs.zfs.free_min_time_ms 1000
vfs.zfs.scan_min_time_ms 1000
vfs.zfs.scan_idle 50
vfs.zfs.scrub_delay 4
vfs.zfs.resilver_delay 2
vfs.zfs.top_maxinflight 32
vfs.zfs.delay_scale 500000
vfs.zfs.delay_min_dirty_percent 60
vfs.zfs.dirty_data_sync 67108864
vfs.zfs.dirty_data_max_percent 10
vfs.zfs.dirty_data_max_max 4294967296
vfs.zfs.dirty_data_max 426512793
vfs.zfs.max_recordsize 1048576
vfs.zfs.zfetch.array_rd_sz 1048576
vfs.zfs.zfetch.max_distance 8388608
vfs.zfs.zfetch.min_sec_reap 2
vfs.zfs.zfetch.max_streams 8
vfs.zfs.prefetch_disable 1
vfs.zfs.mdcomp_disable 0
vfs.zfs.nopwrite_enabled 1
vfs.zfs.dedup.prefetch 1
vfs.zfs.l2c_only_size 0
vfs.zfs.mfu_ghost_data_lsize 0
vfs.zfs.mfu_ghost_metadata_lsize 0
vfs.zfs.mfu_ghost_size 0
vfs.zfs.mfu_data_lsize 26300416
vfs.zfs.mfu_metadata_lsize 1780736
vfs.zfs.mfu_size 29428736
vfs.zfs.mru_ghost_data_lsize 0
vfs.zfs.mru_ghost_metadata_lsize 0
vfs.zfs.mru_ghost_size 0
vfs.zfs.mru_data_lsize 122090496
vfs.zfs.mru_metadata_lsize 2235904
vfs.zfs.mru_size 139389440
vfs.zfs.anon_data_lsize 0
vfs.zfs.anon_metadata_lsize 0
vfs.zfs.anon_size 163840
vfs.zfs.l2arc_norw 1
vfs.zfs.l2arc_feed_again 1
vfs.zfs.l2arc_noprefetch 1
vfs.zfs.l2arc_feed_min_ms 200
vfs.zfs.l2arc_feed_secs 1
vfs.zfs.l2arc_headroom 2
vfs.zfs.l2arc_write_boost 8388608
vfs.zfs.l2arc_write_max 8388608
vfs.zfs.arc_meta_limit 766908416
vfs.zfs.arc_free_target 7062
vfs.zfs.arc_shrink_shift 7
vfs.zfs.arc_average_blocksize 8192
vfs.zfs.arc_min 383454208
vfs.zfs.arc_max 3067633664
When reading the tunable values, 0 means no, 1 typically means yes, and any other number represents a value. To receive a brief description of a “sysctl” value, use sysctl -d. For example:
sysctl -d vfs.zfs.zio.use_uma
vfs.zfs.zio.use_uma: Use uma(9) for ZIO allocations
The ZFS tunables require a fair understanding of how ZFS works, meaning that reading man pages and searching for the meaning of unfamiliar acronyms is required. Do not change a tunable’s value without researching it first. If the tunable takes a numeric value (rather than 0 for no or 1 for yes), do not make one up. Instead, research examples of beneficial values that match the workload.
If any of the ZFS tunables are changed, continue to monitor the system to determine the effect of the change. It is recommended that the changes are tested first at the command line using sysctl. For example, to disable pre-fetch (i.e. change disable to 1 or yes):
sysctl vfs.zfs.prefetch_disable=1
vfs.zfs.prefetch_disable: 0 -> 1
The output will indicate the old value followed by the new value. If the change is not beneficial, change it back to the original value. If the change turns out to be beneficial, it can be made permanent by creating a sysctl using the instructions in Tunables.
26.5. tw_cli¶
FreeNAS® includes the tw_cli command line utility for providing controller, logical unit, and drive management for AMCC/3ware ATA RAID Controllers. The supported models are listed in the man pages for the twe(4) and twa(4) drivers.
Before using this command, read its man page as it describes the terminology and provides some usage examples.
When tw_cli in Shell is entered, the prompt will change, indicating that interactive mode is enabled where all sorts of maintenance commands on the controller and its arrays can be run.
Alternately, one command can be specified to run. For example, to view the disks in the array:
tw_cli /c0 show
Unit UnitType Status %RCmpl %V/I/M Stripe Size(GB) Cache AVrfy
------------------------------------------------------------------------------
u0 RAID-6 OK - - 256K 5587.88 RiW ON
u1 SPARE OK - - - 931.505 - OFF
u2 RAID-10 OK - - 256K 1862.62 RiW ON
VPort Status Unit Size Type Phy Encl-Slot Model
------------------------------------------------------------------------------
p8 OK u0 931.51 GB SAS - /c0/e0/slt0 SEAGATE ST31000640SS
p9 OK u0 931.51 GB SAS - /c0/e0/slt1 SEAGATE ST31000640SS
p10 OK u0 931.51 GB SAS - /c0/e0/slt2 SEAGATE ST31000640SS
p11 OK u0 931.51 GB SAS - /c0/e0/slt3 SEAGATE ST31000640SS
p12 OK u0 931.51 GB SAS - /c0/e0/slt4 SEAGATE ST31000640SS
p13 OK u0 931.51 GB SAS - /c0/e0/slt5 SEAGATE ST31000640SS
p14 OK u0 931.51 GB SAS - /c0/e0/slt6 SEAGATE ST31000640SS
p15 OK u0 931.51 GB SAS - /c0/e0/slt7 SEAGATE ST31000640SS
p16 OK u1 931.51 GB SAS - /c0/e0/slt8 SEAGATE ST31000640SS
p17 OK u2 931.51 GB SATA - /c0/e0/slt9 ST31000340NS
p18 OK u2 931.51 GB SATA - /c0/e0/slt10 ST31000340NS
p19 OK u2 931.51 GB SATA - /c0/e0/slt11 ST31000340NS
p20 OK u2 931.51 GB SATA - /c0/e0/slt15 ST31000340NS
Name OnlineState BBUReady Status Volt Temp Hours LastCapTest
---------------------------------------------------------------------------
bbu On Yes OK OK OK 212 03-Jan-2012
Or, to review the event log:
tw_cli /c0 show events
Ctl Date Severity AEN Message
------------------------------------------------------------------------------
c0 [Thu Feb 23 2012 14:01:15] INFO Battery charging started
c0 [Thu Feb 23 2012 14:03:02] INFO Battery charging completed
c0 [Sat Feb 25 2012 00:02:18] INFO Verify started: unit=0
c0 [Sat Feb 25 2012 00:02:18] INFO Verify started: unit=2,subunit=0
c0 [Sat Feb 25 2012 00:02:18] INFO Verify started: unit=2,subunit=1
c0 [Sat Feb 25 2012 03:49:35] INFO Verify completed: unit=2,subunit=0
c0 [Sat Feb 25 2012 03:51:39] INFO Verify completed: unit=2,subunit=1
c0 [Sat Feb 25 2012 21:55:59] INFO Verify completed: unit=0
c0 [Thu Mar 01 2012 13:51:09] INFO Battery health check started
c0 [Thu Mar 01 2012 13:51:09] INFO Battery health check completed
c0 [Thu Mar 01 2012 13:51:09] INFO Battery charging started
c0 [Thu Mar 01 2012 13:53:03] INFO Battery charging completed
c0 [Sat Mar 03 2012 00:01:24] INFO Verify started: unit=0
c0 [Sat Mar 03 2012 00:01:24] INFO Verify started: unit=2,subunit=0
c0 [Sat Mar 03 2012 00:01:24] INFO Verify started: unit=2,subunit=1
c0 [Sat Mar 03 2012 04:04:27] INFO Verify completed: unit=2,subunit=0
c0 [Sat Mar 03 2012 04:06:25] INFO Verify completed: unit=2,subunit=1
c0 [Sat Mar 03 2012 16:22:05] INFO Verify completed: unit=0
c0 [Thu Mar 08 2012 13:41:39] INFO Battery charging started
c0 [Thu Mar 08 2012 13:43:42] INFO Battery charging completed
c0 [Sat Mar 10 2012 00:01:30] INFO Verify started: unit=0
c0 [Sat Mar 10 2012 00:01:30] INFO Verify started: unit=2,subunit=0
c0 [Sat Mar 10 2012 00:01:30] INFO Verify started: unit=2,subunit=1
c0 [Sat Mar 10 2012 05:06:38] INFO Verify completed: unit=2,subunit=0
c0 [Sat Mar 10 2012 05:08:57] INFO Verify completed: unit=2,subunit=1
c0 [Sat Mar 10 2012 15:58:15] INFO Verify completed: unit=0
If the disks added to the array do not appear in the web interface, try running this command:
tw_cli /c0 rescan
Use the drives to create units and export them to the operating system. When finished, run camcontrol rescan all to make them available in the FreeNAS® web interface.
This forum post contains a handy wrapper script that will give error notifications.
26.6. MegaCli¶
MegaCli is the command line interface for the Broadcom :MegaRAID SAS family of RAID controllers. FreeNAS® also includes the mfiutil(8) utility which can be used to configure and manage connected storage devices.
The MegaCli command is quite complex with several dozen options. The commands demonstrated in the Emergency Cheat Sheet can get you started.
26.7. freenas-debug¶
The FreeNAS® web interface provides an option to save debugging information to a
text file using .
This debugging information is created by the freenas-debug
command line utility and a copy of the information is saved to
/var/tmp/fndebug.
This command can be run manually from Shell to gather specific debugging information. To see a usage explanation listing all options, run the command without any options:
freenas-debug
Usage: /usr/local/bin/freenas-debug <options>
Where options are:
-A Dump all debug information
-B Dump System Configuration Database
-C Dump SMB Configuration
-I Dump IPMI Configuration
-M Dump SATA DOMs Information
-N Dump NFS Configuration
-S Dump SMART Information
-T Loader Configuration Information
-Z Remove old debug information
-a Dump Active Directory Configuration
-c Dump (AD|LDAP) Cache
-e Email debug log to this comma-delimited list of email addresses
-f Dump AFP Configuration
-g Dump GEOM Configuration
-h Dump Hardware Configuration
-i Dump iSCSI Configuration
-j Dump Jail Information
-l Dump LDAP Configuration
-n Dump Network Configuration
-s Dump SSL Configuration
-t Dump System Information
-v Dump Boot System File Verification Status and Inconsistencies
-y Dump Sysctl Configuration
-z Dump ZFS Configuration
Individual tests can be run alone. For example, when troubleshooting an Active Directory configuration, use:
freenas-debug -a
To collect the output of every module, use -A:
freenas-debug -A
For collecting debug information about a single pool, use
zdb with -U /data/zfs/zpool.cache
followed by the name of the pool:
zdb -U /data/zfs/zpool.cache pool1
See the zdb(8) manual page for more information.
26.8. tmux¶
tmux is a terminal multiplexer which enables a number of :terminals to be created, accessed, and controlled from a single :screen. tmux is an alternative to GNU screen. Similar to screen, tmux can be detached from a screen and continue running in the background, then later reattached. Unlike Shell, tmux provides access to a command prompt while still giving access to the graphical administration screens.
To start a session, simply type tmux. As seen in Figure 26.8.1, a new session with a single window opens with a status line at the bottom of the screen. This line shows information on the current session and is used to enter interactive commands.
Fig. 26.8.1 tmux Session
To create a second window, press Ctrl+b then ". To close
a window, type exit within the window.
tmux(1) lists all of the key bindings and commands for interacting with tmux windows and sessions.
If Shell is closed while tmux is running, it will detach its session. The next time Shell is open, run tmux attach to return to the previous session. To leave the tmux session entirely, type exit. If multiple windows are running, it is required to exit out of each first.
These resources provide more information about using tmux:
26.9. Dmidecode¶
Dmidecode reports hardware information as reported by the system BIOS. Dmidecode does not scan the hardware, it only reports what the BIOS told it to. A sample output can be seen here.
To view the BIOS report, type the command with no arguments:
dmidecode | more
dmidecode(8) describes the supported strings and types.
26.10. Midnight Commander¶
Midnight Commander is a program used to manage files from the shell. Open the application by running mc. The arrow keys are used to navigate and select files. Function keys are used to perform operations such as renaming, editing, and copying files. These resources provide more information about using Midnight Commander: