Raid 10 minimum number of disks

Benj94Benj94 MemberMember Posts: 67 ■■■□□□□□□□
In the exam cram book I am reading, it says that Raid 10 has a minimum number of 2 disks (usually 4).
I'm watching a Professor Messer video which suggests that the minimum number of disks is actually 4. I have also gotten this answer from various websites.

Can somebody clear this up for me? I assume that with Raid 10, you would normally utilise two sets of two drives, but all that matters at the moment is whether this is the correct answer for the Comptia A+ exam.

So, what is the minimum number of disks for a Raid 10 setup?

Server and Storage Analyst
CompTIA A+
MSCA: Server 2016 - 70-710 70-711 70-712

Comments

  • iBrokeITiBrokeIT GICSP, GCIP, GXPN, GPEN, GWAPT, GCFE, GCIA, GCIH, GSEC, CySA+, Sec+, eJPT Member Posts: 1,303 ■■■■■■■■■□
    The minimum is 4 disks.

    Raid 10 is also know as a "stripe of mirrors". If you only have 2 disks then you would only be able to create a stripe or a mirror but not both.
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  • PCTechLincPCTechLinc Senior Member King City, CAMember Posts: 646 ■■■■■■□□□□
    It's easier with nested RAID not to think of it as a two digit number. A RAID 10 is actually RAID 1+0. That also helps to distinguish between RAID 1+0 and 0+1. Same is true with RAID 5+0 and the like.
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  • Benj94Benj94 Member Member Posts: 67 ■■■□□□□□□□
    Cheers guys.

    Note to everybody reading the David Prowse exam cram book. In the book, Raid 10 is said to have a minimum number of 2 disks, however, the minimum is actually 4.

    Server and Storage Analyst
    CompTIA A+
    MSCA: Server 2016 - 70-710 70-711 70-712
  • OctalDumpOctalDump Member Posts: 1,722
    The short answer is that RAID 10 on two disks is the same as RAID 1 - the data is "mirrored across" one drive. There's also a three disk RAID 10, where the data is mirrored and striped across all three drives at once. This is the same as most implementations of RAID-1E. These uses of RAID 10 are pretty uncommon outside Linux md.

    But for classic, normal, sane RAID-10, yeah, you need minimum 4 drives.
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