Date: Sun, 28 Sep 2014 05:00:50 -0400 From: FF <fusionfoto@gmail.com> To: freebsd-fs@freebsd.org Subject: Re: Unexpected zfs ARC behavior Message-ID: <CAD=tpefP7F6gdaU0mOqoOu7j5_h1OJLR6UJUGLU7LQEUiVt79A@mail.gmail.com> In-Reply-To: <CAD=tpeejUezjRWh17u_w7HcdzqgVWc768p3FcsCTheeoOrduPQ@mail.gmail.com> References: <CAD=tpeeibpFb542R-atN=v6qwyOBguKhT2AtevTqqwXR0J4iwA@mail.gmail.com> <CAD=tpeejUezjRWh17u_w7HcdzqgVWc768p3FcsCTheeoOrduPQ@mail.gmail.com>
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I'm not sure, but this may be addressed by : https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=191510. On the same system, on a brand new SSD (Intel 320 series, supports TRIM, 973 hours of total run time and no SMARTCTL errors), the l2arc is accruing some errors and I can't tell if they are inter-related or not. sysctl -a |grep l2_ kstat.zfs.misc.arcstats.evict_l2_cached: 8717673244160 kstat.zfs.misc.arcstats.evict_l2_eligible: 2307662193664 kstat.zfs.misc.arcstats.evict_l2_ineligible: 3432677600768 kstat.zfs.misc.arcstats.l2_hits: 11990587 kstat.zfs.misc.arcstats.l2_misses: 66503164 kstat.zfs.misc.arcstats.l2_feeds: 3721611 kstat.zfs.misc.arcstats.l2_rw_clash: 153 kstat.zfs.misc.arcstats.l2_read_bytes: 1152794672128 kstat.zfs.misc.arcstats.l2_write_bytes: 27096209368064 kstat.zfs.misc.arcstats.l2_writes_sent: 1741090 kstat.zfs.misc.arcstats.l2_writes_done: 1741090 kstat.zfs.misc.arcstats.l2_writes_error: 0 kstat.zfs.misc.arcstats.l2_writes_hdr_miss: 2479 kstat.zfs.misc.arcstats.l2_evict_lock_retry: 1149 kstat.zfs.misc.arcstats.l2_evict_reading: 137 kstat.zfs.misc.arcstats.l2_free_on_write: 1000507 kstat.zfs.misc.arcstats.l2_abort_lowmem: 225 kstat.zfs.misc.arcstats.l2_cksum_bad: 8 kstat.zfs.misc.arcstats.l2_io_error: 6 kstat.zfs.misc.arcstats.l2_size: 35261600768 kstat.zfs.misc.arcstats.l2_asize: 33760987648 kstat.zfs.misc.arcstats.l2_hdr_size: 58288928 kstat.zfs.misc.arcstats.l2_compress_successes: 31952645 kstat.zfs.misc.arcstats.l2_compress_zeros: 903 kstat.zfs.misc.arcstats.l2_compress_failures: 436119 kstat.zfs.misc.arcstats.l2_write_trylock_fail: 2481253 kstat.zfs.misc.arcstats.l2_write_passed_headroom: 61954692 kstat.zfs.misc.arcstats.l2_write_spa_mismatch: 26664326 kstat.zfs.misc.arcstats.l2_write_in_l2: 19967700467 kstat.zfs.misc.arcstats.l2_write_io_in_progress: 94722 kstat.zfs.misc.arcstats.l2_write_not_cacheable: 11359575294 kstat.zfs.misc.arcstats.l2_write_full: 730445 kstat.zfs.misc.arcstats.l2_write_buffer_iter: 3721611 kstat.zfs.misc.arcstats.l2_write_pios: 1741090 kstat.zfs.misc.arcstats.l2_write_buffer_bytes_scanned: 3464594001047552 kstat.zfs.misc.arcstats.l2_write_buffer_list_iter: 229359623 kstat.zfs.misc.arcstats.l2_write_buffer_list_null_iter: 65007815 Anyway, thanks in advance for any help offered. Best. On Sat, Sep 27, 2014 at 2:24 PM, FF <fusionfoto@gmail.com> wrote: > > Hi, forwarding from -questions. > > It looks like the image didn't make it across, so here it is: > > http://snag.gy/Ghb7X.jpg > > Thanks in advance for any pointers or suggestions, or confirmations that > somehow this behavior is normal. > > -- > > > So on a somewhat loaded ZFS file server (all NFS) serving mostly VMs with > the load steadily increasing over the month (migrated from other > servers)... the ARC size has unexpectedly dropped (please see attached > graphic, if it makes through the mailing list server). The system peaks > around 2,000 NFS IOPS and hasn't exhibited any slow downs. The L2ARC has a > very low hit rate and prefetch has been turned off to increase the L2ARC > efficiency... but none of that should really matter as far as I can tell > since the L1ARC should try to use all the memory it can. > >> >> Some tuning of zfs sysctls (mostly write_boost and write_max) to increase >> them, but this has since been backed off to default. >> >> vmstat -m reports that 24G is dedicated to opensolaris: >> solaris 1113433 24565820K - 6185559839 >> 16,32,64,128,256,512,1024,2048,4096 >> >> And top reports memory free: >> >> last pid: 32075; load averages: 0.16, 0.13, >> 0.14 up 36+21:44:59 09:16:49 >> 24 processes: 1 running, 23 sleeping >> CPU: 0.0% user, 0.0% nice, 0.0% system, 0.6% interrupt, 99.4% idle >> Mem: 25M Active, 1187M Inact, 26G Wired, 2048K Cache, 1536M Buf, 4160M >> Free >> ARC: 14G Total, 1679M MFU, 12G MRU, 28M Anon, 156M Header, 21M Other >> >> zfs-stats -a : >> >> ------------------------------------------------------------------------ >> ZFS Subsystem Report Sat Sep 27 09:17:07 2014 >> ------------------------------------------------------------------------ >> >> System Information: >> >> Kernel Version: 902001 (osreldate) >> Hardware Platform: amd64 >> Processor Architecture: amd64 >> >> ZFS Storage pool Version: 5000 >> ZFS Filesystem Version: 5 >> >> FreeBSD 9.2-RELEASE-p10 #0 r270148M: Mon Aug 18 23:14:36 EDT 2014 root >> 9:17AM up 36 days, 21:45, 2 users, load averages: 0.12, 0.12, 0.13 >> >> ------------------------------------------------------------------------ >> >> System Memory: >> >> 0.08% 26.22 MiB Active, 3.75% 1.16 GiB Inact >> 82.36% 25.47 GiB Wired, 0.01% 2.00 MiB Cache >> 13.80% 4.27 GiB Free, 0.00% 1.03 MiB Gap >> >> Real Installed: 32.00 GiB >> Real Available: 99.63% 31.88 GiB >> Real Managed: 97.01% 30.93 GiB >> >> Logical Total: 32.00 GiB >> Logical Used: 83.03% 26.57 GiB >> Logical Free: 16.97% 5.43 GiB >> >> Kernel Memory: 23.54 GiB >> Data: 99.90% 23.52 GiB >> Text: 0.10% 23.13 MiB >> >> Kernel Memory Map: 29.76 GiB >> Size: 76.40% 22.74 GiB >> Free: 23.60% 7.02 GiB >> >> ------------------------------------------------------------------------ >> >> ARC Summary: (HEALTHY) >> Memory Throttle Count: 0 >> >> ARC Misc: >> Deleted: 90.09m >> Recycle Misses: 2.44m >> Mutex Misses: 794.67k >> Evict Skips: 17.90m >> >> ARC Size: 44.78% 13.40 GiB >> Target Size: (Adaptive) 44.78% 13.40 GiB >> Min Size (Hard Limit): 12.50% 3.74 GiB >> Max Size (High Water): 8:1 29.93 GiB >> >> ARC Size Breakdown: >> Recently Used Cache Size: 86.16% 11.55 GiB >> Frequently Used Cache Size: 13.84% 1.85 GiB >> >> ARC Hash Breakdown: >> Elements Max: 786.71k >> Elements Current: 87.05% 684.85k >> Collisions: 153.35m >> Chain Max: 16 >> Chains: 194.92k >> >> ------------------------------------------------------------------------ >> >> ARC Efficiency: 506.24m >> Cache Hit Ratio: 87.56% 443.25m >> Cache Miss Ratio: 12.44% 62.99m >> Actual Hit Ratio: 80.06% 405.29m >> >> Data Demand Efficiency: 93.92% 372.74m >> Data Prefetch Efficiency: 49.49% 69.76m >> >> CACHE HITS BY CACHE LIST: >> Anonymously Used: 6.10% 27.05m >> Most Recently Used: 31.37% 139.05m >> Most Frequently Used: 60.07% 266.24m >> Most Recently Used Ghost: 0.80% 3.56m >> Most Frequently Used Ghost: 1.66% 7.35m >> >> CACHE HITS BY DATA TYPE: >> Demand Data: 78.98% 350.09m >> Prefetch Data: 7.79% 34.53m >> Demand Metadata: 12.15% 53.86m >> Prefetch Metadata: 1.08% 4.77m >> >> CACHE MISSES BY DATA TYPE: >> Demand Data: 35.95% 22.65m >> Prefetch Data: 55.93% 35.23m >> Demand Metadata: 4.49% 2.83m >> Prefetch Metadata: 3.63% 2.29m >> >> ------------------------------------------------------------------------ >> <cut> >> >> Any suggestions? Is this expected or acceptable behavior? >> >> Thanks in advance, >> >> -- >> FF >> > > > > -- > FF > -- FF
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