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Re: Corrupted files

To: Sean Caron <scaron@xxxxxxxxx>
Subject: Re: Corrupted files
From: Leslie Rhorer <lrhorer@xxxxxxxxxxxx>
Date: Tue, 09 Sep 2014 20:43:08 -0500
Cc: "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
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References: <540F1B01.3020700@xxxxxxxxxxxx> <20140909220645.GH20518@dastard> <540FA586.9090308@xxxxxxxxxxxx> <CAA43vkVYX+zJQcoTH2iSX7rS9B1D=mnTeyS0QqP+fbKxVY0YZA@xxxxxxxxxxxxxx>
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On 9/9/2014 8:25 PM, Sean Caron wrote:
Hi Leslie,

You really don't want to be running "green" anything in an array... that
is a ticking time bomb just waiting to go off... let me tell you... At
my installation, a predecessor had procured a large number of green
drives because they were very inexpensive and regrets were had by all.

The alternative is nothing at all. I am not a company, just a guy with a couple of arrays at his house. 'Not a rich guy, either.

I've had these arrays since 2001 with only one other mass drive failure, and that was not unrecoverable, nor were they "green" drives. (Four Seagate drives all suddenly decided they did not want to be part of the array, so md kicked all four simultaneously. After that, they would not stay up as part of the array long enough to be mounted. I was able to read all four with dd_rescue, and get the array back online without a single lost file.

Note also these arrays are not usually under any sort of massive load. The bulk of the data is video files which are written once at about 80MBps and then read one-by-one at about 4MBps.

Lousy performance, lots of spurious ejection/RAID gremlins and the
failure rate on the WDC Greens is just appalling...

None of the failed drives were WD green. All three and the previous four were Seagate. I realize that is not a large statistical sample.

BBWC stands for Battery Backed Write Cache; this is a feature of
hardware RAID cards

Ah, yes. This array does not have a BBWC controller. The backup array does, actually, but the battery backup is disabled.

it is just like it says on the tin; a bit (usually
half a gig, or a gig, or two...) of nonvolatile cache that retains
writes to the array in case of power failure, etc. If you have BBWC
enabled but your battery is dead, bad things can happen. Not applicable
for JBOD software RAID.

        Exactly.  All the arrays are JBOD / mdadm.

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