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Allan Xu
Asked: 2016-12-16 07:18:57 +0800 CST

Raid 1 or Windows Mirroring: Can I just detach one of the HDDs and use it?

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I am deciding on RAID level and one feature (requirement) I like to have is to be able to (have the freedom) detach one of the RAID HDDs, plug it as a USB disk to my laptop and read/backup/recover its data.

This way I know I am NOT dealing with some special disk format that makes the data available only with the RAID controller.

I know RAID5 fails my requirements. If I take one of the HDDs, I can't use its data, unless I go through an epic challenge.

  • Can RAID 1 satisfy my requirement?

  • Can Windows Disk management mirroring satisfy my requirement? If yes, it is the same with all version of windows?

windows mirroring raid1

2 Answers

  1. What is the main purpose of detaching the HDD in RAID? Playing with RAID disks can cause data corruption in some cases.

    Afaik, the HDD in hardware RAID can be visible only if it is attached to the same (or similar in some cases) RAID controller. Software RAID can possibly deal with it, but again, there is no need to use this as a solution.

    If you need o backup your data from the RAID HDDs, you can use backup software, it is much more easier, than detaching the HDD.

    If you need a reliable disaster recovery solution - use Veeam replication. If you need a simple host-to-host replication, use Unison: http://www.cis.upenn.edu/~bcpierce/unison/ or something similar.

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  2. First of all, there are two kinds of mirroring which you may be talking about (see Storage Space Mirroring vs Disk Management Mirroring) and you did not specify which one you are referring to, so I will endeavor to answer the question for Disk Management Mirroring, which I recently tested for our company.

    When I individually took the mirrored drives, one at a time, and looked at it with the Paragon Backup and Recovery USB Stick utility, one drive would recognize just fine, and the other one wouldn't. (My Paragon may not be completely up-to-date.) So, there appears to be some kind of behind-the-scenes "master"-and-"slave" or "source"-and-"copy" kind of thing going on. The drive that would not recognize with Paragon was eventually brought up fine by Windows 10 without much work. But once you bring either drive up in Windows, all by itself, it appears there's no going back to mirrored status, unfortunately. To re-establish mirroring, you have to backup, nuke both drives, create the mirrored drive, and restore your backup to the mirrored drive. (The Synchronization way seemed to be really slow, and that was with two 500MB SSD's).

    So, as long as you don't actually load it in Windows, but load it up in some special boot-time utility, I think you have a good chance of not disturbing the (fragile?) mirroring. The Paragon USB stick does what you want, though only with one of the drives (not both, unless you mount them at the same time using Paragon). But I don't think Windows by itself is going to do it for you. HTH.

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