ZFS cheatsheet

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Löschen nicht löschbarer Snapshots

Hier nach einem abgebrochenen ZFS send/recv: <syntaxhighlight lang=bash>

  1. zfs destroy MYSQL-LOG/binlog@copy_20130403

cannot destroy 'MYSQL-LOG/binlog@copy_20130403': dataset is busy

  1. zfs holds -r MYSQL-LOG@copy_20130403

NAME TAG TIMESTAMP MYSQL-LOG@copy_20130403 .send-22887-0 Wed Apr 3 09:03:32 2013

  1. zfs release .send-22887-0 MYSQL-LOG@copy_20130403
  2. zfs destroy MYSQL-LOG/binlog@copy_20130403

</source>

ZFS Tuning

Eine gefühlte Langsamkeit auf Systemen mit ZFS kommt vom sehr großen Cachehunger. Den kann man eingrenzen: Erstmal schauen, was phase ist: <syntaxhighlight lang=bash> lollypop@wirefall:~# echo "::kmastat ! grep Total" |mdb -k Total [hat_memload] 13508608B 309323764 0 Total [kmem_msb] 24010752B 1509706 0 Total [kmem_va] 660340736B 140448 0 Total [kmem_default] 690409472B 1416078794 0 Total [kmem_io_64G] 34619392B 8456 0 Total [kmem_io_4G] 16384B 92 0 Total [kmem_io_2G] 24576B 62 0 Total [bp_map] 1048576B 234488 0 Total [umem_np] 786432B 976 0 Total [id32] 4096B 2620 0 Total [zfs_file_data_buf] 1471275008B 1326646 0 Total [segkp] 589824B 192886 0 Total [ip_minor_arena_sa] 64B 13332 0 Total [ip_minor_arena_la] 192B 45183 0 Total [spdsock] 64B 1 0 Total [namefs_inodes] 64B 24 0 lollypop@wirefall:~# echo "::memstat" | mdb -k Page Summary Pages MB %Tot

---------------- ---------------- ----

Kernel 255013 996 24% ZFS File Data 359196 1403 34% Anon 346538 1353 33% Exec and libs 33948 132 3% Page cache 4836 18 0% Free (cachelist) 22086 86 2% Free (freelist) 23420 91 2%

Total 1045037 4082 Physical 1045036 4082 </source> Oder nur ZFS <syntaxhighlight lang=bash> echo "::memstat ! egrep '(Page Summary|-----|ZFS)'"| mdb -k </source>

Ausgeben aller ARC-Parameter: <syntaxhighlight lang=bash> lollypop@wirefall:~# echo "::arc -m" | mdb -k hits = 80839319 misses = 3717788 demand_data_hits = 4127150 demand_data_misses = 51589 demand_metadata_hits = 9467792 demand_metadata_misses = 2125852 prefetch_data_hits = 127941 prefetch_data_misses = 596238 prefetch_metadata_hits = 67116436 prefetch_metadata_misses = 944109 mru_hits = 2031248 mru_ghost_hits = 1906199 mfu_hits = 78514880 mfu_ghost_hits = 993236 deleted = 880714 recycle_miss = 1381210 mutex_miss = 197 evict_skip = 38573528 evict_l2_cached = 0 evict_l2_eligible = 94658370048 evict_l2_ineligible = 8946457600 hash_elements = 79571 hash_elements_max = 82328 hash_collisions = 3005774 hash_chains = 22460 hash_chain_max = 8 p = 64 MB c = 512 MB c_min = 127 MB c_max = 512 MB size = 512 MB hdr_size = 14825736 data_size = 468982784 other_size = 53480992 l2_hits = 0 l2_misses = 0 l2_feeds = 0 l2_rw_clash = 0 l2_read_bytes = 0 l2_write_bytes = 0 l2_writes_sent = 0 l2_writes_done = 0 l2_writes_error = 0 l2_writes_hdr_miss = 0 l2_evict_lock_retry = 0 l2_evict_reading = 0 l2_free_on_write = 0 l2_abort_lowmem = 0 l2_cksum_bad = 0 l2_io_error = 0 l2_size = 0 l2_hdr_size = 0 memory_throttle_count = 0 arc_no_grow = 0 arc_tempreserve = 0 MB arc_meta_used = 150 MB arc_meta_limit = 128 MB arc_meta_max = 313 MB </source>

Man kann sich auch alle Parameter ausgeben lassen, die für ZFS gesetzt sind mit: <syntaxhighlight lang=bash>

  1. echo ::zfs_params | mdb -k

arc_reduce_dnlc_percent = 0x3 zfs_arc_max = 0x100000000 zfs_arc_min = 0x0 arc_shrink_shift = 0x5 zfs_mdcomp_disable = 0x0 zfs_prefetch_disable = 0x0 zfetch_max_streams = 0x8 zfetch_min_sec_reap = 0x2 zfetch_block_cap = 0x100 zfetch_array_rd_sz = 0x100000 zfs_default_bs = 0x9 zfs_default_ibs = 0xe ...

  1. echo "::arc -a" | mdb -k

hits = 592730 misses = 5095 demand_data_hits = 0 demand_data_misses = 0 demand_metadata_hits = 592719 demand_metadata_misses = 4866 prefetch_data_hits = 0 prefetch_data_misses = 0 ... </source>

Setzen von Kernelparametern geht auch online mit: <syntaxhighlight lang=bash>

  1. echo zfs_arc_max/Z100000000 | mdb -kw

zfs_arc_max: <old value> = 0x100000000 </source> Das setzt den zfs_arc_max auf 4GB = 0x100000000

Limitieren des ARC Cache

In der /etc/system einfach: set zfs:zfs_arc_max = <Number of bytes>

Easy calculation: <syntaxhighlight lang=bash>

  1. NUMGB=32
  2. printf "set zfs:zfs_arc_max = 0x%x\n" $[ ${NUMGB} * 1024 ** 3 ]

set zfs:zfs_arc_max = 0x800000000 </source>

Siehe auch Limiting the ARC Cache


But !!!! NEVER DO THIS !!!!

Never use mdb -kw to set the values!!!

But on a test system you could try to get the position in the Kernel with <syntaxhighlight lang=bash> > arc_stats::print -a arcstat_p.value.ui64 arcstat_c.value.ui64 arcstat_c_max.value.ui64 </source>

Calculate for example 8GB: <syntaxhighlight lang=bash>

  1. printf "0x%x\n" $[ 8 * 1024 ** 3 ]

0x200000000 </source>

And raise the values like this: 

arc.c = arc.c_max
arc.p = arc.c / 2

<syntaxhighlight lang=bash>

  1. mdb -kw

Loading modules: [ unix krtld genunix dtrace specfs uppc pcplusmp cpu.generic zfs mpt_sas sockfs ip hook neti dls sctp arp usba uhci fcp fctl qlc nca md lofs sata cpc fcip random crypto logindmux ptm ufs sppp nfs ipc ] > arc_stats::print -a arcstat_p.value.ui64 arcstat_c.value.ui64 arcstat_c_max.value.ui64 fffffffffbcfaf90 arcstat_p.value.ui64 = 0x4000000 fffffffffbcfafc0 arcstat_c.value.ui64 = 0x40000000 fffffffffbcfb020 arcstat_c_max.value.ui64 = 0x40000000 > fffffffffbcfb020/Z 0x200000000 arc_stats+0x4a0:0x40000000 = 0x200000000

> fffffffffbcfafc0/Z 0x200000000 arc_stats+0x440:0x44a42480 = 0x200000000

> fffffffffbcfaf90/Z 0x100000000 arc_stats+0x410:0x4000000 = 0x100000000 </source>

ZFS Platzverbrauch besser anzeigen

$ zfs list -o space
NAME               AVAIL   USED  USEDSNAP  USEDDS  USEDREFRESERV  USEDCHILD
rpool              25.4G  7.79G         0     64K              0      7.79G
rpool/ROOT         25.4G  6.29G         0     18K              0      6.29G
rpool/ROOT/snv_98  25.4G  6.29G         0   6.29G              0          0
rpool/dump         25.4G  1.00G         0   1.00G              0          0
rpool/export       25.4G    38K         0     20K              0        18K
rpool/export/home  25.4G    18K         0     18K              0          0
rpool/swap         25.8G   512M         0    111M           401M          0

Wenn zfs list -o space als shortcut noch nicht zur Verfügung steht, geht meist: 

$ zfs list -o name,avail,used,usedsnap,usedds,usedrefreserv,usedchild -t filesystem,volume

Migration UFS-Root -> ZFS-Root via Live-Upgrade

Erstmal den ZFS Rootpool anlegen: 

# zpool create rpool /dev/dsk/<zfs-disk>

Wer Problemen aus dem Weg gehen möchte, läßt den Namen bei rpool.

Boot-Environment (BE) mit lucreate erstellen 

# lucreate -c ufsBE -n zfsBE -p rpool

Hiermit werden die Files in die ZFS-Umgebung kopiert.

Prüfen, ob das BootFS richtig gesetzt wurde: 

# zpool get bootfs rpool
NAME   PROPERTY  VALUE             SOURCE
rpool  bootfs    rpool/ROOT/zfsBE  local

Auskommentieren von eventuell noch nachgebliebenen rootdev-Einträgen in der /etc/system 

# zpool export rpool
# mkdir /tmp/rpool
# zpool import -R /tmp/rpool rpool
# zfs unmount rpool
# rmdir /tmp/rpool/rpool
# zfs mount rpool/ROOT/zfsBE
# perl -pi.orig -e 's#^(rootdev.*)$#* \1#g' /tmp/rpool/etc/system
# zpool export rpool

Bootblock für ZFS auf die ZFS-Platte 

# installboot -F zfs /usr/platform/`uname -i`/lib/fs/zfs/bootblk /dev/rdsk/<zfs-disk>

Aktivieren des neuen BEs 

# luactivate zfsBE


cannot destroy 'snapshot': dataset is busy

<syntaxhighlight lang=bash> root@sun1 # zfs destroy zpool1/raiddisk0@send_1 cannot destroy 'zpool1/raiddisk0@send_1': dataset is busy root@sun1 # zfs holds zpool1/raiddisk0@send_1 NAME TAG TIMESTAMP zpool1/raiddisk0@send_1 .send-14952-0 Mon Jun 15 15:29:09 2015 zpool1/raiddisk0@send_1 .send-16117-0 Mon Jun 15 15:29:28 2015 zpool1/raiddisk0@send_1 .send-26208-0 Tue Jun 16 10:14:47 2015 zpool1/raiddisk0@send_1 .send-8129-0 Mon Jun 15 15:26:54 2015 root@sun1 # zfs release .send-14952-0 zpool1/raiddisk0@send_1 root@sun1 # zfs release .send-16117-0 zpool1/raiddisk0@send_1 root@sun1 # zfs release .send-26208-0 zpool1/raiddisk0@send_1 root@sun1 # zfs release .send-8129-0 zpool1/raiddisk0@send_1 root@sun1 # zfs holds zpool1/raiddisk0@send_1 root@sun1 # root@sun1 # zfs destroy zpool1/raiddisk0@send_1 root@sun1 # </source>

Fragmentation

<syntaxhighlight lang=bash>

  1. zdb -mm <pool> | nawk '/fragmentation/{count++;frag+=$NF}END{printf "Overall fragmentation %.2d\n",(frag/count);}'

</source>

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