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From:   Phillip Susi <phill@thesusis.net>
To:     d tbsky <tbskyd@gmail.com>
Cc:     Xiao Ni <xni@redhat.com>,
        list Linux RAID <linux-raid@vger.kernel.org>
Subject: Re: raid10 redundancy
Date:   Thu, 06 May 2021 09:09:12 -0400
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d tbsky writes:

> Xiao Ni <xni@redhat.com>
>>
>> Hi
>>
>> It depends on which layout do you use and the copies you specify. There
>> is a detailed description in `man md 3`

No, it only depends on the number of copies.  They layout just effects
the performance.

> Thanks a lot for the hint. After studying the pattern I think n2 and
> o2 could survive if losing two correct disks with 4 or 5 disks. but f2
> will be dead. is my understanding correct?

No; 2 copies means you can lose one disk and still have the other copy.
Where those copies are stored doesn't matter for redundancy, only performance.