Pour mieux comprendre la fonction Raid ...

Discussion in 'Server Operation' started by misterm, Sep 26, 2019.

  1. misterm

    misterm Member

    Hello
    I have 2 hard drives, mounted in Raid, which is:

    But when I want to check if they are well mounted, I do not have the same result:

    logic?

    Thank you

    Mz
     
  2. till

    till Super Moderator Staff Member ISPConfig Developer

    It's not uncommon that different tools are reporting different disk usages, depending on block sizes and the way they calculate the size.
     
  3. misterm

    misterm Member

    That doesn't answer my question, if it exceeds the size of the 1st hard drive, will it copy this on the other drive or I'll get an error message that tells me I'm no longer room.
     
  4. till

    till Super Moderator Staff Member ISPConfig Developer

    There is no such question in your first post ;)

    Google for 'raid level' to understand what a raid level is and how it works. The raid level is 1 in your configuration which means mirroring: https://en.wikipedia.org/wiki/Standard_RAID_levels#RAID_1 So the capacity of your raid is the capacity of the largest member of the raid and this implies that you cannot exceed the size of the first disk.
     
  5. misterm

    misterm Member

    If I understand what is noted in the Wikipedia page, if the first disc exceeds its capacity, it will not copy on the other disk, right?
     
  6. Croydon

    Croydon ISPConfig Developer ISPConfig Developer

    No. The array is the size of the smaller of both disks.
     
  7. misterm

    misterm Member

    I'm lost, we know actually explained how it works, the only thing I ask, when it will exceed the capacity of the 1st disc, what's going this past, that's what I want to understand, it's not hard no ...
     
  8. till

    till Super Moderator Staff Member ISPConfig Developer

    If you know how it works, then you know the answer, so I have no idea why you ask then... If something is mirrored, then the data is written on each disk at the same time. This means when you write a file of let's say 10MB on the raid, then this file takes 10MB on the first disk plus 10MB on the second disk. So what does this mean? When Disk A is full, then Disk B must be full as well as the same amount of disk space is used on each Disk in raid Level 1. And as with any disk, you can not exceed its capacity, or where do you think that data is stored when there is no space left? And don't tell me 'In the cloud' ;)
     
    misterm likes this.
  9. Croydon

    Croydon ISPConfig Developer ISPConfig Developer

    That's what we already explained. You cannot exceed because the raid is always limited to the size of the smaller disk. That's it.
     
  10. misterm

    misterm Member

    Till, Croydon, I just had my response via your message and also via my datacenter support, but, it is possible not to activate this function is have the ability that would like to get, not have this mirror mode ...
     
  11. Croydon

    Croydon ISPConfig Developer ISPConfig Developer

    I hope you don't think about using RAID 0. This would span data over both disks (available raid space = sum of both disks). That would be a very very high risk of data loss.
     
    misterm likes this.
  12. Croydon

    Croydon ISPConfig Developer ISPConfig Developer

    And if you want to use both disks separately: Re-install the complete server but disable software raid on install completely. Though it is not recommended of course.
     
    misterm likes this.

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