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Hi , What is the difference between configuring hard disks as software raid and hardware raid in Sun Solaris servers , and what is the procedure to configure a new added hard disks as software raid?

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Hi man,

Below is the most important differences between software and hardware RAID:

1- cost:
software RAID comes with the Solaris OS, so no need to pay extra money. In hardware RAID you have to pay for the card, to be able to configure hardware RAID.
2- Performance:
With the software based RAID0 and RAID1 performance is the same compared to hardware RAID. However, performance goes down when you use parity-based arrays and/or several arrays at the same time. The performance of a software-based array is dependent on the server CPU performance and current load. In Hardware RAID you get high performance.
3- Complexity:
hardware RAID is more easy to configure than software RAID.
4- Disk hot swapping:
It means replacing hard disk without shutting down the server. You can do this in hardware RAID but not on software RAID.

Configuring two normal partitions as software RAID (RAID 1 Mirroring):

1- insert the two disks in empty slots.
2- execute the below command  to define them on the system:

devfsadm

3- execute the format command to create the partition you want (do this on the both new disks). also, create another partition of size 300mb on each of the new disks only if metadb command in step 4 gave nothing as an output.

4- check if the database replicas exist on the server by executing:

metadb

if you received an output go to step 6 if not go to next step to create the database replicas.

5-  to create the database replicas execute the below commands:

metadb –f –a –c 3 c0t0d0s7 (slice 7 on first disk of size 300 mb. this partition you already created before)
metadb –f –a –c 3 c0t1d0s7 (slice 7 on second disk of size 300 mb.  this partition you already created before)


here we created 6 replicas 3 on first disk and 3 on the second.

6- now we start mirroring: execute the below commands:

   metainit –f d0 1 1 c0t0d0s0  (the partition you created on first disk. here we changed it into a volume called d0)
   metainit –f d1 1 1  c0t1d0s0  (the partition you created on second disk. here we changed it into a volume d1)
   metainit d2 –m d0 (here d2 is the mirror and d0 is the submirror)
   metattach d2 d1 (here we attached the second submirror which is d1)

7- after this execute the metastat command to see the status of your configuration. you should see them in sync status.

8- finally you edit the /etc/vfstab and put a line at the end similar to the below.

/dev/md/dsk/d2      /dev/md/rdsk/d2       /u03     .......and you put the rest of the line as you do normally.

9- then you create a ufs filesystem on the d2:

newfs /dev/md/dsk/d2

10- you mount the metadevice:

mount /u03

if you did not understand any of the points please tell me.

Regards,
Houssien Sleem

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Great Houssien, I tried the mentioned configurations and it's working just fine.

Appreciate it