Re: SoftRAID with network iSCSI multipath
On 26/11/13 17:21, Ritesh Raj Sarraf wrote:
On Monday 25 November 2013 10:29 PM, Eneko Lacunza wrote:
We have a Debian Wheezy node with the following:
- A directory that is a mountpoint for a SoftRAID (RAID1) device,
with 2 devices. (md0)
* Device one is a local disk (sdb)
* Device two is a multipath network iSCSI disk (dm-3)
When the server boots up, md0 is degraded because it couldn't find dm-3.
You must have very good reasons as to why you are building an odd
configuration like this. But I'm assuming, you do have one.
I know it's odd :) Do you think it wouldn't be so odd without multipath?
I have looked to mdraid and multipath init scripts and it seems that
multipath is trying to start multipath devices before networking is up.
Of course, it does. And the reason is that multipath is not a network
service. DM Multipath is one of the output targets of the Device Mapper
framework, just like LVM2. There are many other consumers of multipath
(Fiber Channel etc). Also, there are many people who use ROOT on
Multipath, which requires us to start multipath as early as possible, in
the boot process.
In your case, the problem will not be solved by the _netdev option. The
dependency is simple. You need your network first. Then your iscsi
devices. Then the MD Raid activation. And then at last you want to call
mount.
You will have to roll out your own initscript for this requirement.
If the md device had two iSCSI devices, the problem would be the same?
Thanks
Eneko
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