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From: Sebastian Kuzminsky <seb@highlab.com>
To: linux-raid@vger.kernel.org
Subject: Raid sync observations
Date: Tue, 20 Dec 2005 10:18:26 -0700	[thread overview]
Message-ID: <E1Eol86-0008Ju-3J@highlab.com> (raw)

I just created a RAID array (4-disk RAID-6).  When "mdadm -C" returned,
/proc/mdstat showed it syncing the new array at about 17 MB/s.  "vmstat 1"
showed hardly any blocks in or out, and an almost completely idle cpu.


Question 1: Why didnt the raid sync I/O show up with vmstat?


Question 2: Why was it limited to 17 MB per second?  The maximum was
left at the default, 200 MB/s.  The min was also at the default, 1 MB/s.
I get 60 MB/s per disk with "hdparm -tT" (that's using one disk at a time,
but still).  The checksumming code does > 3 GB/s.


Just curious really.  This is with 2.6.15-rc5 and SATA disks via libata.


-- 
Sebastian Kuzminsky

             reply	other threads:[~2005-12-20 17:18 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-12-20 17:18 Sebastian Kuzminsky [this message]
2005-12-20 18:14 ` Raid sync observations Sebastian Kuzminsky
2005-12-20 21:27 ` Neil Brown
2005-12-20 21:33   ` Sebastian Kuzminsky
2005-12-21  1:55 ` Christopher Smith
2005-12-21 11:49   ` Andy Smith
2005-12-21 17:02     ` Sebastian Kuzminsky
2005-12-21 17:13       ` Gordon Henderson
2006-01-08 18:18         ` Bill Davidsen
  -- strict thread matches above, loose matches on Subject: below --
2005-12-20 18:27 Andrew Burgess
2005-12-20 19:13 ` Sebastian Kuzminsky
2005-12-20 22:09 Jeff Breidenbach

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