Re: smartctl kills performance

This is as expected /designed... hence the name of the test "offline"... It's name would be "online" if it was meant to be run with lots of host activity.

Jeff

| -----Original Message-----
| From: [email protected] [mailto:[email protected]]
| Sent: Monday, February 08, 2016 10:13 AM
| To: CoolCold
| Cc: [email protected]
| Subject: Re: [smartmontools-support] smartctl kills performance
| 
| This is normal. The tests are conducted by the hard drive's firmware, not
| smartmontools, so you won't see much CPU usage. However, you are doing a lot
| of reads, effectively putting the hard drive under heavy load. Hard drives under
| heavy load are going to be slow.
| 
| Exactly how slow depends on the hard drive, its firmware, and whatever else is
| hitting it from the OS.
| 
| > Hello!
| > Can't reply directly into the thread like with Google Groups, but
| > anyway. I'm writing in reply to
| > http://sourceforge.net/p/smartmontools/mailman/message/29431706/ about
| > offline test kills the performace.
| >
| > On the new server on Hetzner, strange performance degradation was
| > detected. During several days, degrade started at 4:15 AM, reboot
| > helped.
| >
| > The server is equipped with disks:
| > root@phi1:~# for i in  /dev/sd?;do smartctl -i $i;done|grep Model
| > Device Model:     HGST HUS726060ALE610
| > Device Model:     HGST HUS726060ALE610
| > Device Model:     HGST HUS726060ALE610
| > Device Model:     HGST HUS726060ALE610
| >
| > As revealed, when regular offline scan fires up (at 4:15 AM), disk
| > performance is slow as turtle.
| >
| > Feb  6 04:15:01 phi1 smartd[2232]: Device: /dev/sdb [SAT], starting
| > scheduled Long Self-Test.
| > Feb  6 04:15:01 phi1 smartd[2232]: Device: /dev/sdc [SAT], starting
| > scheduled Long Self-Test.
| >
| > I can see large awaits in iostat, collectd showed disk io time up to
| > 75 seconds! (
| > http://gyazo.coolcold.org/upload/fe129abcc401bd61496273c32d4c.png
| > )
| >
| > Stopping offline test with "-x" restores the performance.
| >
| > May be this going to be useful to someone else.
| >
| >
| > P.S. I'm off the list, so if you want to reply, add me to CC/TO fields.
| > --
| > Best regards,
| > [COOLCOLD-RIPN]
| >
| > ----------------------------------------------------------------------
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| 
| 
| 
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