If you come across issue where error say 'no common kex alg' while connecting from solaris to any machines like freebsd, freenas, Linux etc.
Try to add following line to your sshd_config.

KexAlgorithms curve25519-sha256@libssh.org,diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521

So on nexenta one of our disk failed and require to be replace.
Dell sent us lager drive than original drive.

PERC required to clear managed cache, once it is cleared i was able to create new VD for new drive.
While creating VD please make sure you choose the size same as working VD.
It is required when you copy the slice from working drive, else it will error.
'Partition 0 not aligned on cylinder boundary'.
There are way to add larger size but i took the fastest route after so many problems.

After adding new drive there are certain steps i had to do before i can add it to the syspool.

First clear and scan all the drives on box.

devfsadm -C -c disk -v
devfsadm -c disk -v

Check if your newly added drives added.

echo |format | head -10

:!:You can ignore using head, mine was c0t0d0 which was fist in the list.

Fdisk new drive, but some time it error 'Partition 0 of the disk has an incorrect offset'.
I had to do it multiple times.

pfexec fdisk /dev/rdsk/c0t0d0s0

Now its time to replicate slices.

prtvtoc /dev/dsk/c0t1d0s0 |fmthard -s - /dev/rdsk/c0t0d0s0

Now attache the drive to zpool mirror, it is require to specify existing mirror drive as source.

zpool attach -f syspool c0t1d0s0 c0t0d0s0

It should tell you to run installgrub.

installgrub /boot/grub/stage1 /boot/grub/stage2 /dev/rdsk/c0t0d0s0

Wait for resilvering before you reboot the server.