I am having an issue with Megacli when adding or removing virtual disks. I will post a link to fpaste that has the issue shown.

In brief whenever i add, or remove, a virtual disk via MegaCli the attempt succeeds and the adapter is configured but the OS remounts dm-0
in read only. dm-0 is my root lv. This issue does not happen if i boot into the default, non Xen, CentOS kernel. On stock CentOS kernel i can add and remove VD’s all day without any issue at all. ONLY happens while booted up with the Xen kernel.

I have been racking my brain trying to figure this out. Any help is appreciated.

My system:

Dell Poweredge 2950 II
PERC 5/i Controller

CentOS 6.7
Xen Version: 4.4.3-1.el6

*Fpaste showing the console log messages during the event:*

http://www.fpaste.org/277855/14445392/

*Full XL dump below:*

xl info host : cmhinfra1.*
release : 3.18.17-13.el6.x86_64
version : #1 SMP Tue Jul 21 17:17:17 UTC 2015
machine : x86_64
nr_cpus : 8
max_cpu_id : 7
nr_nodes : 1
cores_per_socket : 4
threads_per_core : 1
cpu_mhz : 1995
hw_caps :
bfebfbff:20100800:00000000:00000900:0004e33d:00000000:00000001:00000000
virt_caps : hvm total_memory : 32762
free_memory : 29340
sharing_freed_memory : 0
sharing_used_memory : 0
outstanding_claims : 0
free_cpus : 0
xen_major : 4
xen_minor : 4
xen_extra : .3-1.el6
xen_version : 4.4.3-1.el6
xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
hvm-3.0-x86_32p hvm-3.0-x86_64
xen_scheduler : credit xen_pagesize : 4096
platform_params : virt_start=0xffff800000000000
xen_changeset : Thu Apr 23 15:06:13 2015 +0100 git:c5ec076-dirty xen_commandline : dom0_mem24M,max:1024M loglvl=all guest_loglvl=all console=tty0 console=com2 com2W600
cc_compiler : gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-16)
cc_compile_by : mockbuild cc_compile_domain : CentOS.org cc_compile_date : Tue Sep 8 15:31:24 UTC 2015
xend_config_format : 4

*grub.conf:*

jeremym]# cat /etc/grub.conf
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/mapper/vg_cmhinfra1-lv_root
# initrd /initrd-[generic-]version.img
#boot=/dev/sdb default=0
timeout=5
#splashimage=(hd0,0)/grub/splash.xpm.gz
#hiddenmenu serial –unit=1 –speedW600
terminal –timeout console serial

title CentOS (3.18.17-13.el6.x86_64)
root (hd0,0)
kernel /xen.gz dom0_mem24M,max:1024M loglvl=all guest_loglvl=all console=tty0 console=com2 com2W600
module /vmlinuz-3.18.17-13.el6.x86_64 ro root=/dev/mapper/vg_cmhinfra1-lv_root rd_LVM_LV=vg_cmhinfra1/lv_swap rd_LVM_LV=vg_cmhinfra1/lv_root console=hvc0 nomodset
module /initramfs-3.18.17-13.el6.x86_64.img title CentOS (2.6.32-573.7.1.el6.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.32-573.7.1.el6.x86_64 ro root=/dev/mapper/vg_cmhinfra1-lv_root rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us LANG=en_US.UTF-8 rd_NO_MD rd_LVM_LV=vg_cmhinfra1/lv_swap SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=vg_cmhinfra1/lv_root rd_NO_DM rhgb quiet console=ttyS1,57600
console=tty0

initrd /initramfs-2.6.32-573.7.1.el6.x86_64.img