[PVE-User] (unsupported) SoftRAID related kernel panic increasing softraid1 device number
elacunza at binovo.es
Thu Nov 14 09:23:11 CET 2013
Yesterday I was on a client doing some final reconfiguration after
having replaced a VMWare cluster with Proxmox.
One of the steps involved changing the shape of a software raid mirror.
The mirror had a local SSD disk exposed in a hwraid0 volume, and a
second, write-mostly, hwraid1 disc, composed of two local SATA discs.
1. Grow softraid1 to include a iSCSI disk in an EMC AX4-5i, effectively
having 3-way softraid mirror.
2. Remove the hwraid1 SATA volume from the softraid mirror, leaving it
back with 2 devices.
iSCSI device worked perfectly, could be partitioned, formated and
written. But everytime I tried to grow the softraid device (believe me I
tried several times!!), kernel panicked, an our pretty production
virtual machines stopped working! ;)
The problem was the grow command, not the iSCSI device:
mdadm --grow /dev/md0 -n 3
That command was panicking the kernel. I tried having a hot spare and
also giving the new block device on the same command, without luck. Also
.25 and .26 proxmox kernels.
It seems to me that Proxmox (RHEL-based) kernel doesn't support this
operation, although Debian mdadm does (I think that Debian kernel does
support it, too).
Finally I failed and removed the SATA volume and added as replacement
the iSCSI device, without changing the number of devices of the
softmirror, and that did the (a bit more dangerous) trick.
I thought this could be useful to someone. Also, I tried to find what
version of linux kernel does support device number growing in softraid1,
but had no luck...
Fortunately everything is working perfectly know, RAID devices are
optimal and performance is great!
Zuzendari Teknikoa / Director Técnico
Binovo IT Human Project, S.L.
Astigarraga bidea 2, planta 6 dcha., ofi. 3-2; 20180 Oiartzun (Gipuzkoa)
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