Messages in this thread | | | Subject | Re: idle RAID1 cpu usage | From | Paul Slootman <> | Date | 27 Dec 2006 19:44:09 GMT |
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Jan Engelhardt <jengelh@linux01.gwdg.de> wrote: >On Dec 27 2006 19:09, Paul Slootman wrote: >> >>This works fine, but I noticed that quite some time was being used by >>the mdX_raid1 threads; even on a partition that's not even being used at >>this time... (it was an empty mounted filesystem, but I umounted it to >>be sure the filesystem code wasn't causing some IO). >> >>My question is: why is CPU being used by the RAID1 threads, even for >>those devices that are otherwise unused? What are they doing? > >First-time synchronization (if applies), otherwise I suspect some >housekeeping (bitmap perhaps?).
No, I had rebooted after the initial synchronization was complete.
>Otherwise it seems like a question who does what. On a raid5 array (i.e. >cpu-heavy), both smbd and mdx_raid5 accumulate time for, of course, xor >calculation.
On those devices that are actually in use, I'd understand CPU being used; but where the device is not even mounted or used for swap or whatever, I find that amount of CPU usage very high for just checking the bitmap... I may take the idle device apart and reassemble without a bitmap to see whether that makes any difference.
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