From: David Brown <david.brown@hesbynett.no>
To: Mathias Buren <mathias.buren@gmail.com>
Cc: GuoZhong Han <hanguozhong@meganovo.com>,
stan@hardwarefreak.com, linux-raid@vger.kernel.org
Subject: Re: make filesystem failed while the capacity of raid5 is big than 16TB
Date: Thu, 13 Sep 2012 09:13:11 +0200 [thread overview]
Message-ID: <50518787.4010501@hesbynett.no> (raw)
In-Reply-To: <5051542A.4090901@gmail.com>
On 13/09/2012 05:34, Mathias Buren wrote:
> 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)
>
I wouldn't bother with hotspares with RAID6 unless service and
replacement of a dead disk is going to take a long time - you already
have double redundancy with the raid6. Raid6 on 8 disks is already
orders of magnitude safer than raid5 with 16 disks - once you have a
higher risk of the power supply taking fire and burning /all/ your
disks, you don't benefit from even greater redundancy!
> 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.
>
If that is possible for the OP, then that is definitely worth trying.
It is this kind of setup that will benefit most from the newer
multithreading support.
next prev parent reply other threads:[~2012-09-13 7:13 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-12 7:04 make filesystem failed while the capacity of raid5 is big than 16TB vincent
2012-09-12 7:32 ` Jack Wang
2012-09-12 7:37 ` Chris Dunlop
2012-09-12 7:58 ` David Brown
[not found] ` <CACY-59cLmV2SRY+FrvhHxseDD1+r-B-3bOKPGzJdGttW+9U2mw@mail.gmail.com>
2012-09-12 9:46 ` David Brown
2012-09-12 14:13 ` Stan Hoeppner
2012-09-13 7:06 ` David Brown
2012-09-13 3:21 ` GuoZhong Han
2012-09-13 3:34 ` Mathias Buren
2012-09-13 7:13 ` David Brown [this message]
2012-09-13 7:30 ` David Brown
2012-09-13 7:43 ` John Robinson
2012-09-13 9:15 ` David Brown
2012-09-13 13:25 ` Stan Hoeppner
2012-09-13 13:52 ` David Brown
2012-09-13 22:47 ` Stan Hoeppner
2012-09-18 9:35 ` GuoZhong Han
2012-09-18 10:22 ` David Brown
2012-09-18 21:38 ` Stan Hoeppner
2012-09-19 7:20 ` David Brown
2012-09-19 16:00 ` Stan Hoeppner
2012-09-18 21:20 ` Stan Hoeppner
2012-09-18 21:20 ` Stan Hoeppner
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