Greetings,
I'm looking for advice on configuring mdadm.conf to allow for the
coexisting of a non dm-multipath boot/root md device and a dm-multipath
configured md device data volume.
The issue I am running into is that on boot mdraid assumes control of
all disks with md superblocks on them before multipath starts. This
appears to be due to the boot/root being md devices, multipath never
gets to own the other disks in the system and then assemble on mpath
devices in /dev/disk/by-id.
I have tried using DEVICE declarations in mdadm.conf but so far the
result is either the boot volumes don't get recognized (assemble +
switchroot fails) but the data volume gets assembled with dm-multipath
devices, or the boot/root md devices assemble and the dm-multipath based
md devices get assembled as sd member devices and dm-multipath is disabled.
Some of the DEVICE declarations I tried in mdadm.conf are below. Two on
the same line or two separate lines. The non dm-mulitpath boot devices
are Intel SATA SSDs on the onboard SATA ports. The dm-mulitpath RAID-10
data volume is on an external SAS HBA with valid multipath
configuration. I have remade the initramfs after these changes (dracut -f).
DEVICE /dev/disk/by-id/scsi-SATA_INTEL_SSD.*-.*
/dev/disk/by-id/dm-uuid-.*-mpath-.*
and
DEVICE /dev/disk/by-id/scsi-SATA_INTEL_SSD.*-.*
DEVICE /dev/disk/by-id/dm-uuid-.*-mpath-.*
These examples find the SAS attached dm-multipath devices fine and
assemble the mdraid volumes but the boot devices are not found or
assembled. A look via rdshell shows the
/dev/disk/by-id/scsi-SATA_INTEL_SSD.*-.* devices listed in the
/dev/disk/by-id directory. It appears mdadm doesn't like the declaration
for the SSDs and won't find them. I haven't been able to figure out why
so far.
Current state (/proc/mdstat)
cat /proc/mdstat
Personalities : [raid1] [raid10]
md4 : active raid10 dm-11[3] dm-5[2] dm-7[1] dm-9[0]
584615936 blocks super 1.2 512K chunks 2 near-copies [4/4] [UUUU]
bitmap: 0/5 pages [0KB], 65536KB chunk
md3 : active raid1 dm-10[3] dm-2[2] dm-4[1] dm-8[0]
521792 blocks super 1.2 [4/4] [UUUU]
md0 : active raid1 sdb1[1] sda1[0]
255936 blocks super 1.0 [2/2] [UU]
md2 : active raid1 sdb3[1] sda3[0]
225653760 blocks super 1.1 [2/2] [UU]
bitmap: 0/2 pages [0KB], 65536KB chunk
md1 : active raid1 sda2[0] sdb2[1]
8380416 blocks super 1.1 [2/2] [UU]
unused devices: <none>
OS: CentOS 6.6 x86_64 2.6.32-504.el6.x86_64
If anyone has suggestions of how to configure a proper set of DEVICE
declarations to assemble the SATA connected member drives of the
boot/root volumes without relying on the default "DEVICE partitions
containers" where the multipath devices get assembled as sd devices
prior to multipath starting I would appreciate the advice.
Thanks,
--Jeff
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