Neil,

----- Original Message -----

From: "NeilBrown" <redacted>
To: "Andrew Martin" <redacted>
Cc: linux-raid@vger.kernel.org
Sent: Tuesday, February 11, 2014 1:54:20 PM
Subject: Re: Automatically drop caches after mdadm fails a drive out of an array?

On Tue, 11 Feb 2014 11:11:04 -0600 (CST) Andrew Martin [off-list ref]
wrote:

quoted

Hello,

I am running mdadm 3.2.5 on an Ubuntu 12.04 fileserver with a 10-drive
RAID6 array (10x1TB). Recently, /dev/sdb started failing:
Feb 10 13:49:29 myfileserver kernel: [17162220.838256] sas: command
0xffff88010628f600, task 0xffff8800466241c0, timed out: BLK_EH_NOT_HANDLED

Around this same time, a few users attempted to access a directory on this
RAID array over CIFS, which they had previously accessed earlier in the
day. When they attempted to access it this time, the directory was empty.
The emptiness of the folder was confirmed via a local shell on the
fileserver, which reported the same information. At around 13:50, mdadm
dropped /dev/sdb from the RAID array:

The directory being empty can have nothing to do with the device failure.
md/raid will never let bad data into the page cache in the manner you
suggest.

Thank you for the clarification. What other possibilities could have triggered
this behavior? I am also using LVM and DRBD on top of the the md device.

Thanks,

Andrew