From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mathias Buren <mathias.buren@gmail.com>
Subject: Re: make filesystem failed while the capacity of raid5 is big than
 16TB
Date: Thu, 13 Sep 2012 11:34:02 +0800
Message-ID: <5051542A.4090901@gmail.com>
References: <505033fe.8aec440a.5d52.ffffe37b@mx.google.com> <50504094.2040302@hesbynett.no> <CACY-59cLmV2SRY+FrvhHxseDD1+r-B-3bOKPGzJdGttW+9U2mw@mail.gmail.com> <505059DD.8000108@hesbynett.no> <CACY-59dAbS=8ncRAeZrAYBAvo7G6FEyoGREHtC-ze4cwhiF9GQ@mail.gmail.com>
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To: GuoZhong Han <hanguozhong@meganovo.com>
Cc: David Brown <david.brown@hesbynett.no>, stan@hardwarefreak.com, linux-raid@vger.kernel.org
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On 13/09/12 11:21, GuoZhong Han wrote:
> Hi David:
>
>           I am sorry for last mail that I had not described the
> requirements of the system very clear.
>
>           I will detail for you to describe the requirements of the system.
>

(snip)

>
>           As you said, the performance for write of 16*2T raid5 will be
> terrible, so what do you think that how many disks to be build to a
> raid5 will be more appropriate?

Personally I wouldn't use more than 5 drives in a RAID5 with drives 
larger than 1TB, the failure risk is too high. With 16x 2TB drives, how 
about two RAID6 arrays of 8 drives each, then RAID0 them? (RAID60)

Or, two RAID6 arrays with 7 drives each, 2 hotspares, and RAID0 on top. 
(RAID10 + 2 HSP)

You mention 36 cores. Perhaps you should try the very latest mdadm 
versions and Linux kernels (perhaps from the MD Linux git tree), and 
enable the multicore option.

Mathias