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I read that software RAID should not be implemented on a machine that also has ESXi virtual machines running. Does this mean that I would want to avoid LVM and or LXC/Docker containers as well on this server?

Thanks

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mh00h
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  • Where did you read it? The reasoning should be there. More context would be super useful. – Journeyman Geek Apr 12 '15 at 00:27
  • I read it here. I have updated the question with the link. http://serverfault.com/questions/519688/software-raid-underneath-esxi-datastore – mh00h Apr 13 '15 at 07:40
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    The question you are referencing was asking about using software RAID within a VM. Software RAID within a VM is not recommended, it belongs at a lower layer than that. Why you couldn't use software RAID at the hypervisor level is however not explained by any of the answers to that other question. I don't know any specific reason why that shouldn't work, though the answers you point to imply it doesn't. Based on that I am voting to reopen this question, because it seems clear to me what information you are missing. – kasperd Apr 13 '15 at 08:33
  • docker broke my weekly checking of RAID - http://unix.stackexchange.com/questions/178811/unable-to-check-a-mdadm-raid1-array-says-the-file-systems-read-only – brablc Jun 15 '15 at 20:01

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LXC/Docker by design doesn't have anything to do with RAID (any RAID) at all.
Docker/LXC containers are run on the same kernel as the host.
As such I don't think there are any docker related problems.

Reaces
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KonstantinYu
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Actually, RAID10 is the preferred RAID level for high-performance virtual machines. While it has its shortcoming, I can not see why it should not be used with ESXi or Docker.

Back to original question: docker mainly is a user-space affaire. So it can not corrupt a software or hardware RAID device.

As a side note, I strongly advise you against cheap RAID cards. If you really want to do hardware RAID, buy a card with a DRAM cache and a BBU/NV module.

shodanshok
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All software running on the machine operates as if the RAID is 1 device. This is why usually the device is /dev/sdc instead of seeing /dev/sda and then also /dev/sdb.

If you're using a software RAID vs a RAID card then it's plausible that something on the OS could cause the OS injected RAID to not behave properly. I know people use them all the time but I highly suggest using a RAID card — even a cheap one if you have too, it's worth of loading this functionality to its own hardware

JDługosz
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Ethode
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