Re: Re: Two Drive Failure on RAID-5

["Janos Haar" <janos.haar@netcenter.hu>]

----- Original Message ----- 
From: "David Lethe" <david@santools.com>
To: "Cry" <cry_regarder@yahoo.com>; <linux-raid@vger.kernel.org>
Sent: Tuesday, May 20, 2008 7:18 PM
Subject: RE: Re: Two Drive Failure on RAID-5


>
>
> -----Original Message-----
> From: linux-raid-owner@vger.kernel.org
> [mailto:linux-raid-owner@vger.kernel.org] On Behalf Of Cry
> Sent: Tuesday, May 20, 2008 10:32 AM
> To: linux-raid@vger.kernel.org
> Subject: Re: Two Drive Failure on RAID-5
>
> David Greaves <david <at> dgreaves.com> writes:
>
>>
>> Yep. Don't panic and don't do anything else yet if you're not
> confident about
>> what you're doing.
>>
>> I'll follow up with more info in a short while.
>>
>> Info you can provide:
>> kernel version
>> mdadm version
>> cat /proc/mdstat
>> mdadm --examine /dev/sd[abcdef]1 (or whatever your array components
> are)
>> relevant smartctl info on the bad drive(s)
>> dmesg info about the drive failures
>>
>> Assuming genuine hardware failure:
>> Do you have any spare drives that you can use to replace the
> components?
>>
>> David
>
> Thanks for the info.  I was able to do a --force --assemble on the array
> and I
> copied off my most critical data.  At the moment, I don't have enough
> drives to
> take all the data on the array, so I'm going to be at a bit of a
> standstill
> until new hardware arrives.
>
> Since the copy of that data (about 500Gig of about 2TB) went so well, I
> decided
> to try to sync up the spare again and it died at the same point and the
> raid
> system pulled down the array.  I'm trying to decide if I should follow
> your
> suggestion in sister post to copy the failed drive onto my spare or if I
> should
> just format the spare and try to recover another 500 gig of data of the
> array.
>
> Is there a mdadm or other command to tell the raid system to stay up in
> the face
> of errors?  Can the array be assembled in a way that doesn't change the
> array in
> any way (completely read-only)?
>
> I've got the older failed drive also (about 15 hours older).  Can that
> be
> leveraged also?
>
> The server isn't networked right now, but I'll try to get the above
> requested
> logs tonight.
>
> By the way, I'm thinking about buying five of these:
>
> Seagate Barracuda 7200.11 1TB ST31000340AS SATA-II 32MB Cache
>
> and one of these:
>
> Supermicro SUPERMICRO CSE-M35T-1 Hot-Swapable SATA HDD Enclosure
>
> http://www.supermicro.com/products/accessories/mobilerack/CSE-M35T-1.cfm
>
> and building a raid-6 array.  I'll convert the surviving drives into a
> backup
> for the primary array.  Any feedback on the above?  Is there a
> suggestion on an
> inexpensive controller to give more SATA ports that is very software
> raid
> compatible?
>
> Any suggestions for optimal configuration (ext3) and tuning for the new
> array?
> My load consists of serving a photo gallery via apache and gallery2 as
> well as a
> local media (audio/video) server so files sizes tend to be large.
>
> Thanks,
>
> Joel
> ===============
> Joel:
>
> Respectfully .. are you nuts???
>
> Don't buy the 7200.11 disks.   You bought a bunch of desktop class
> drives, and they crapped out on you, and you are about to make the same
> mistake again.  Get the server class disk that is designed to run 24x7
> duty cycle, which in your case would be the 'cuda ES.2
>
> Sorry about the soapbox, but it never ceases to amaze me how people try
> to save by buying disk drives architected with lowest possible cost in
> mind, and don't investigate the higher-quality disks that are designed
> for extended reliability and data integrity.
>
> David

David and Joel,

Let me remember you to the power supply!
This is really important too!

The 24x7 cycle systems need a good quality PS and cables, connectors for 
hdd.
One poor (Y) cable, or connector can make easy 1-2 or more failed drives at 
a same time!
The SMART can monitor the actual state, but can not monitor the bad 
connection and/or noise on the voltage.

Cheers,
Janos


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