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Re: mount: Structure needs cleaning

To: Brian Candler <B.Candler@xxxxxxxxx>
Subject: Re: mount: Structure needs cleaning
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 29 Feb 2012 14:50:44 +1100
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20120228091441.GA1562@xxxxxxxx>
References: <33393100.post@xxxxxxxxxxxxxxx> <4F49B693.4080309@xxxxxxxxxxxxxxxxx> <33393429.post@xxxxxxxxxxxxxxx> <20120227004902.GQ3592@dastard> <33397518.post@xxxxxxxxxxxxxxx> <20120228014813.GU3592@dastard> <20120228091441.GA1562@xxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Tue, Feb 28, 2012 at 09:14:41AM +0000, Brian Candler wrote:
> On Tue, Feb 28, 2012 at 12:48:13PM +1100, Dave Chinner wrote:
> > > Write cache: enabled
> > 
> > There's your problem. You should read all the relevant sections on
> > write caches in the XFS FAQ. e.g:
> > 
> > http://xfs.org/index.php/XFS_FAQ#Q._Which_settings_does_my_RAID_controller_need_.3F
> As a side question to this: if I am using Linux's md software RAID with an
> HBA, and XFS is using write barriers (as I believe it does by default), is
> it still necessary to disable write caching on the drives?

No. The MD layers pass the correct flushes to the drives now.

> My reading of the FAQ suggests that the write barrier by itself should be
> sufficient - but this requires that the md RAID driver implements write
> barriers correctly.  I seem to remember reading a long time ago that LVM
> and/or dmraid didn't, although that may be different now.

It has since about 2.6.35.

> Incidentally I'm using 'mdadm ... -b internal' to ensure that the RAID array
> marks dirty areas, so that if a write part-completes (e.g.  a block is
> written to only one half of a RAID1) then at next power-up this should be
> made consistent again.

Assuming that the dirty area tracking uses write cache flushes


Dave Chinner

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