SSD read/write - how long will it last
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It has 4GB of RAM and it's only using 33%.
I stopped the syslogd service temporarily and something was still writing to disk excessively so it's not the culprit.
This command shows zfskern writing a lot but what and why is it writing?
top -m io -o write -IS -d 1last pid: 97225; load averages: 0.17, 0.17, 0.14 up 2+20:53:44 20:25:57 80 processes: 2 running, 76 sleeping, 2 waiting CPU: 0.3% user, 0.1% nice, 1.2% system, 0.2% interrupt, 98.2% idle Mem: 89M Active, 191M Inact, 1383M Wired, 2166M Free ARC: 842M Total, 678M MFU, 91M MRU, 2298K Anon, 9317K Header, 59M Other 699M Compressed, 1473M Uncompressed, 2.11:1 Ratio Swap: 1024M Total, 1024M Free PID USERNAME VCSW IVCSW READ WRITE FAULT TOTAL PERCENT COMMAND 6 root 2207881 26057 313 1142462 0 1142775 82.97% zfskern 54361 root 35902 7684 313 151637 80 152030 11.04% php-fpm 359 root 34589 8604 111 76066 28 76205 5.53% php-fpm 14040 dhcpd 969664 20228 12 2585 20 2617 0.19% dhcpd 84008 root 3607 224 0 2060 0 2060 0.15% syslogd 358 root 36037 7802 54 400 35 489 0.04% php-fpm 82882 root 2927 152 0 353 0 353 0.03% php_pfb 18850 _dhcp 5303 182 0 287 0 287 0.02% dhclient 80651 root 235 53 0 216 0 216 0.02% vnstatd 3607 root 258782 7119 0 25 0 25 0.00% ntpd 98600 unbound 857611 289739 1 7 8 16 0.00% unbound 4737 root 14994 5587 71 4 2 77 0.01% nginx 38639 root 9 4 7 2 5 14 0.00% login 5065 root 4456 2591 4 2 1 7 0.00% nginx 80827 root 18 3 0 2 0 2 0.00% sh 4892 root 5399 2003 0 2 0 2 0.00% nginx 63231 root 18 3 0 2 0 2 0.00% sh 22895 root 282285 17201 0 0 2 2 0.00% filterlog 1 root 272 7 85 0 15 100 0.01% init 357 root 243687 8432 1 0 0 1 0.00% php-fpm 67497 root 3140 244 5 0 8 13 0.00% tcsh 397 root 626 182 1 0 4 5 0.00% check_reload_status 0 root 92073647 98734 42 0 0 42 0.00% kernel 41040 root 10 26 5 0 4 9 0.00% sh 62768 root 9323 597 2 0 9 11 0.00% sshd 83376 root 6 1 4 0 5 9 0.00% iperf3 38864 root 4 2 1 0 0 1 0.00% getty 2194 root 13892 1543 1 0 0 1 0.00% cron 42041 root 14 1 1 0 0 1 0.00% sh 66300 root 9007 859 0 0 2 2 0.00% qemu-ga 12509 root 10 1 1 0 0 1 0.00% sshd -
@michmoor If you look closelt in that report, it says %used = 3%
So there is lots and lots of life left in your SSD :-) -
@keyser you sure percentage used isn’t taking about disk space?
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@michmoor said in SSD read/write - how long will it last:
@keyser you sure percentage used isn’t taking about disk space?
Well, pretty much 100%. The SSD itself cannot know how much diskspace the OS considers allocated and used - especially not if the OS does not support TRIM. Also, the S.M.A.R.T. Health tools always reports on the actual physical state of the SSD, not the filesystem state on the SSD.
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@adriftatlas said in SSD read/write - how long will it last:
PID USERNAME VCSW IVCSW READ WRITE FAULT TOTAL PERCENT COMMAND 6 root 2207881 26057 313 1142462 0 1142775 82.97% zfskernWRITE is a counter, I believe? So it should increment forever. I pulled up a router on 2.6 with ZFS and see 5315859 (incrementing slowly) but that's 284 days of uptime. zfskern should include the ZFS scrub.
What does
iostat -xshow? On that same router, which is also using a RAM disk, I see:: iostat -x extended device statistics device r/s w/s kr/s kw/s ms/r ms/w ms/o ms/t qlen %b ada0 0 0 0.0 1.2 6 0 24 3 0 0 cd0 0 0 0.0 0.0 0 0 1 1 0 0 pass0 0 0 0.0 0.0 4 1 79 22 0 0 pass1 0 0 0.0 0.0 0 0 0 0 0 0 -
I would go with a small RaspBerry PI 3/4 with 2/4 GB and a
big mSATA or M.2 SSD with TRIM support as a logging server. -
extended device statistics device r/s w/s kr/s kw/s ms/r ms/w ms/o ms/t qlen %b da0 0 11 2.1 149.9 0 0 5 1 0 0 pass0 0 0 0.0 0.0 0 0 0 0 0 0I'd like to understand what is writing though. I'd rather not resort to using a RAM disk as it can cause other issues. There is no reason anything should be writing that much on a mostly idle router.
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@adriftatlas The usual HUGE suspects are pfSense add-on packages (in order of typical write activity:)
1: Suricata
2: Snort
3: pfBlockerNG (especially with reply logging turned on)
4: NtopNGAll of them has measures to manually configure how much (or little) logging they actually do.
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@adriftatlas Hmm yeah that’s 149x more. Not that I have a comparison handy.
Re:suspects, also any package mentioning SSD here:
https://www.netgate.com/supported-pfsense-plus-packages -
The only thing I have installed that could be chatty is pfBlockerNG. Even then I only use the Geo IP blocking aliases.
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I get 49 kw/s, and I'm using pfblockerNG (not logging DNS replies) and remote syslog (with logging to the firewall disabled).
Based on the other thread, the count would be: 49 x 60 x 60 x 24 x 365 = 1545264000
Which is 1.5 TB per year.
My SSD, ADATA M.2 SATA SU650 120GB can write 70TBW, so based on that, I would be able to use it for around 45 years.
