[collectd] ZFS statistics

Florian Forster octo at verplant.org
Fri Jun 6 19:41:10 CEST 2008


Hi Randy,

thanks again for getting me access to the NexentaOS and OpenSolaris
machines :) Apparently ZFS statistics are available via kstat, which is
nice because that's already used by other plugins.

Unfortunately I have no idea what the values mean or, more precisely,
which ones are interesting. Is there some documentation what these
values mean? Or, better yet, what they tell you ;)

This one
---
module: unix                            instance: 0     
name:   vopstats_zfs                    class:    misc
---
looks a lot like the values the NFS plugin collects, i. e. number of
opens, seeks, readdirs and so on. Also in there is `read_bytes' and
`write_bytes' - I think this is definitely interesting. But what about
`readdir_bytes'?

This one
---
module: unix                            instance: 0     
name:   zfs_znode_cache                 class:    kmem_cache
---
I think is not that interesting, is it?

The other two seem to hold quite detailed counters about a cache which I
guess is interesting. But there are so many numbers, I doubt that all of
them really matter.

The relevant values provided by kstat are attached. If you find anything
exciting, let me know ;)

Regards,
-octo
-- 
Florian octo Forster
Hacker in training
GnuPG: 0x91523C3D
http://verplant.org/
-------------- next part --------------
module: unix                            instance: 0     
name:   vopstats_zfs                    class:    misc
	crtime                          16.734665459
	naccess                         1080434
	naddmap                         3640593
	nclose                          1305737
	ncmp                            2416218
	ncreate                         164161
	ndelmap                         3653422
	ndispose                        1991220
	ndump                           0
	ndumpctl                        0
	nfid                            0
	nfrlock                         981708
	nfsync                          159549
	ngetattr                        5355744
	ngetpage                        18350648
	ngetsecattr                     31717
	ninactive                       45085
	nioctl                          115693
	nlink                           32
	nlookup                         13889857
	nmap                            1576935
	nmkdir                          353
	nopen                           1005695
	npageio                         0
	npathconf                       6988
	npoll                           1476045
	nputpage                        2038
	nread                           3835335
	nreaddir                        15588
	nreadlink                       735542
	nrealvp                         533452
	nremove                         118564
	nrename                         1569
	nrmdir                          151
	nrwlock                         5841878
	nrwunlock                       5841905
	nseek                           3436509
	nsetattr                        5032
	nsetfl                          8985
	nsetsecattr                     414
	nshrlock                        0
	nspace                          149
	nsymlink                        570
	nvnevent                        0
	nwrite                          1991093
	read_bytes                      8513383508
	readdir_bytes                   13089824
	snaptime                        189798.51975528
	write_bytes                     1079602379

module: unix                            instance: 0     
name:   zfs_znode_cache                 class:    kmem_cache
	align                           8
	alloc                           129520
	alloc_fail                      0
	buf_avail                       16
	buf_constructed                 7
	buf_inuse                       7344
	buf_max                         7360
	buf_size                        200
	buf_total                       7360
	chunk_size                      200
	crtime                          16.734617341
	depot_alloc                     509
	depot_contention                0
	depot_free                      781
	empty_magazines                 1
	free                            123253
	full_magazines                  0
	hash_lookup_depth               0
	hash_rescale                    0
	hash_size                       0
	magazine_size                   7
	slab_alloc                      8156
	slab_create                     368
	slab_destroy                    0
	slab_free                       805
	slab_size                       4096
	snaptime                        189798.520196756
	vmem_source                     23

module: zfs                             instance: 0     
name:   arcstats                        class:    misc
	c                               74567312
	c_max                           396011520
	c_min                           67108864
	crtime                          16.734464684
	deleted                         9238
	demand_data_hits                913384
	demand_data_misses              10187
	demand_metadata_hits            145902
	demand_metadata_misses          2285
	evict_skip                      26
	hash_chain_max                  6
	hash_chains                     934
	hash_collisions                 97702
	hash_elements                   4793
	hash_elements_max               7505
	hdr_size                        933912
	hits                            1125225
	l2_abort_lowmem                 0
	l2_cksum_bad                    0
	l2_evict_lock_retry             0
	l2_evict_reading                0
	l2_feeds                        0
	l2_free_on_write                0
	l2_hdr_size                     0
	l2_hits                         0
	l2_io_error                     0
	l2_misses                       0
	l2_rw_clash                     0
	l2_size                         0
	l2_writes_done                  0
	l2_writes_error                 0
	l2_writes_hdr_miss              0
	l2_writes_sent                  0
	memory_throttle_count           45
	mfu_ghost_hits                  3020
	mfu_hits                        962145
	misses                          14933
	mru_ghost_hits                  3387
	mru_hits                        97775
	mutex_miss                      4
	p                               59062000
	prefetch_data_hits              897
	prefetch_data_misses            493
	prefetch_metadata_hits          65042
	prefetch_metadata_misses        1968
	recycle_miss                    1715
	size                            72743792
	snaptime                        189798.522399513

module: zfs                             instance: 0     
name:   vdev_cache_stats                class:    misc
	crtime                          16.734513284
	delegations                     1281
	hits                            2454
	misses                          1493
	snaptime                        189798.530708387

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