megacli key commands in linux

List physical devices
megacli -PDlist -a1 |grep "Enclosure Device ID\|Slot Number\|Firmware state"

Assuming 6 spare PDs on Enclosure ID 32 with Slot nos 6-11:

Create RAID 6 array
megacli -CfgLdAdd -r6 [32:6,32:7,32:8,32:9,32:10,32:11] -a0

Create RAID 10 array
megacli -CfgSpanAdd -r10 -Array0[32:6,32:7] -Array1[32:8,32:9] -Array2[32:10,32:11] -a0
 
Check array status 
megacli -LDInfo -LAll -a0 

Delete array no. 2 (-Force may be required)
megacli -CfgLdDel -L2 -Force -a0

Extending an existing RAID array with a new disk
.megacli -LDRecon -Start -r5 -Add -PhysDrv[32:3] -L0 -a0

Creating a global hot spare

megacli -PDHSP -Set -PhysDrv [0:2] -a0

Show background initialization progress

MegaCli64 -LDBI -ShowProg -Lall -a0

Avoiding 'The resulting partition is not properly aligned for best performance' in parted

There are various posts with mathematical ways to do this which don't always work, eg if optimal_io_size is zero.
With newer versions of parted, just use -a (alignment type)
parted -a optimal <device>
Then in parted use % to allocate eg
(parted) mkpart <name> 0% 50%
Bingo- it now does it for you. You can check what it's done by setting units to sectors eg
(parted)unit s
(parted)p
Model: ATA WDC WD4001FAEX-0 (scsi)
Disk /dev/sdb: 7814037168s
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number  Start  End          Size         File system  Name  Flags
 1      2048s  7814035455s  7814033408s              P1

Exporting nfs version 3 through a firewall

nfs v4 uses only 1 port - 2049. Open that to tcp & udp in your firewall and you're good.
nfs v3 and before are a bit more complicated. As well as the main nfs port 2049, you need to allow access to the portmapper (fixed on port 111), mountd, lockd & statd ports- and possibly also the rquotad port- and apart from portmapper they aren't fixed by default. To fix them, so you can create appropriate firewall rules, edit (in RHEL/CentOS/ScientficLinux) /etc/sysconfig/nfs and add/modify these lines. The actual ports you use are pretty arbitrary:
RQUOTAD_PORT=762
LOCKD_TCPPORT=890
LOCKD_UDPPORT=890
MOUNTD_PORT=892
STATD_PORT=891
Restart nfs & nfslock, set up your firewall rules (for both tcp & udp as either can work on all protocols) and that should be that - except that lockd is implemented as a kernel thread. The LOCKD variables above cause writes to /proc/sys/fs/nfs/nlm_tcpport & /proc/sys/fs/nfs/nlm_udpport in /etc/init.d/nfs and /etc/init.d/nfslock but these don't seem to have any effect.

Alternatively, the debian handbook https://debian-handbook.info/browse/stable/sect.nfs-file-server.html suggests creating a modprobe file:
Example 11.24: The /etc/modprobe.d/lockd file
options lockd nlm_udpport=2045 nlm_tcpport=2045

Either way it seems you basically need to reboot to get it to work.
You can check your nfsports with rpcinfo -p which will also tell you which NFS versions and which IP protocols they are using. You can also run rpcinfo for a remote server to check that's all working - rpcinfo -p  <servername>.