0

Introduction

So currently I have a software RAID setup using MDADM on Debian. It is setup as a RAID 10 through a NAS so available over the network. All of the drives are connected through a USB multiplier enclosure. I believe the USB enclosure is starting to have some problems as the drives become disconnected randomly from the computer hosting them. For this reason I have purchased a hardware RAID card that will do the job for me better than the software RAID.

Problem

So when switching over to the new RAID card, it will have to format the drives to structure the new RAID. For this reason, I need to get the data off of the old one. I am having problems with going over the network to do this because of the enclosure randomly going off. So my question is, in a RAID 10 setup, can I take two of the drives (which supposedly have all the data on it), plug it in directly to the backup computer and pull the data off like that? Or will the data not be recognized and accurate since it has been pulled off of the RAID controller?

When trying to copy a single file through the network, I get an error from windows stating "The request could not be performed because of an I/O device error". I can create new files and folders over the network so it doesn't have any permissions incorrect...

Further Information

So my RAID consists of 4 physical drives. From my thought process, I can break apart the RAID 1 layer into the two separate RAID 0 sections. One of those sections will then contain all of the data so it might be easier to work with just one section rather than the RAID 10 together:

enter image description here

When trying to read each "0 section" I tried to mount the section and I get the error "unknown filesystem type 'linux_raid_member' so I am guessing that I will not be able to section it.

Does anyone know of any other way to section the data?

Improve this question
2
  • How are you trying to mount them, directly connected to a computer? You'll need to load the mdadm raid configuration onto the computer you're loading them on, and tell it that you're currently missing two disks also. Warning, you should really just have a backup and do this properly, you might loose all your data. superuser.com/questions/443321/…
    – djsmiley2kStaysInside
    Commented Mar 9, 2017 at 16:19
  • @djsmiley2k Well I have computer A which currently does the software raid. I would like to connect the drives to computer B to do a backup but computer B does not have the software raid on it. Computer A is Debian, Computer B is windows 10
    – Eric F
    Commented Mar 9, 2017 at 16:22

1 Answer 1

Reset to default
1

Linux MD Raid is agnostic of the connection - so directly attaching he disks (or at least one of each leg) to a linux Machine via SATA will work: I did this many times over for data recovery purposes.

Even taking the Disks out of the USB enclosure and putting them into 4 separate el-cheapo USB will work.

Be also reminded, that a hardware raid controller with out a BBU will not be a signifcant improvement over MD RAID.

Improve this answer
7
  • How do I actually connect to the drives and get the data off then? When I tried to mount, debian throws the error that it can't mount because of the file type? Also what is BBU?
    – Eric F
    Commented Mar 9, 2017 at 16:24
  • You don't directly mount them, you need to re-build the raid, as I put in the comment to your question. Be warned, you could nuke all your data!
    – djsmiley2kStaysInside
    Commented Mar 9, 2017 at 16:25
  • Well.... is there a better way that is less risky? I can "see" all of the data from the mounted raid.. I am just getting the I/O errors. I am willing to try this if there are no other options
    – Eric F
    Commented Mar 9, 2017 at 16:28
  • On any modern Linux Distribution, you don't need to manually rebuild: If you have the Disks plugged in on boot (so that all can be detected at the same time), the RAID will be assembled for you - most likely even read-only for increased safety.
    – Eugen Rieck
    Commented Mar 9, 2017 at 17:24
  • A BBU is a battery backup unit - it allows to take small writes (random IO) and safely store the data, until it can be written to Disk at a later time, thus saving access time.
    – Eugen Rieck
    Commented Mar 9, 2017 at 17:26

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .