From: NeilBrown <neilb@suse.de>
To: George Spelvin <linux@horizon.com>
Cc: linux-raid@vger.kernel.org
Subject: Re: RAID6 syncing at 24 MB/s?
Date: Wed, 18 Apr 2012 15:05:02 +1000 [thread overview]
Message-ID: <20120418150502.41d6305d@notabene.brown> (raw)
In-Reply-To: <20120418043540.19923.qmail@science.horizon.com>
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On 18 Apr 2012 00:35:40 -0400 "George Spelvin" <linux@horizon.com> wrote:
> I'm putting together a 7x2TB RAID6 for a home media server, and after
> encountering a fun kernel bug building the array (old kernel, a new one
> fixed it), I fot things working, but now notice that each disk is syncing
> at 23.8 MB/s. hdparm -t reports they can do well over 100 MB/s each,
> and the processor, while only an i3, is spending about 20% of one core
> in the raid6 task.
Can you try an experiment for me (if you don't have anything useful on the
array yet)?
Stop the array. Recreate it exactly the same way as before, and see if it
goes faster. I think it might - at least until it got up to where it was up
to.
NeilBrown
>
> Basicall, it was created with:
> mdadm -C -l 6 -n 7 -c 128 -b internal /dev/md0 /dev/sd[b-h]
> (The kernel bug was in 2.6.35, and was triggered by forgetting the
> "/dev/md0"; one of the RAID ioctls it tries confused up the /dev/sd
> driver quite thoroughly)
>
> It's an Intel chipset motherboard with a jmicros 2xSATA+PATA chip,
> and one port on a SiI3132 plug-in card. And mostly cheap Caviar green
> EARS drives (yes, I know about the lack of TLER). Note that I didn't
> partition the drives, so there's no risk of a 4K-unaligned partition.
>
> A friend with his own Linux media server said he saw the exact same speed
> building his RAID6 array.
>
> The speed_limit_max is set to the default, the system is idle, and the
> resultant md drive is not mounted.
>
> Is there a web page somewhere with speed tuning suggestions?
>
>
> Thank you!
> --
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next prev parent reply other threads:[~2012-04-18 5:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-18 4:35 RAID6 syncing at 24 MB/s? George Spelvin
2012-04-18 4:47 ` Jack Wang
2012-04-18 5:05 ` NeilBrown [this message]
2012-04-18 5:22 ` George Spelvin
2012-04-18 5:37 ` NeilBrown
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