Three Q&As about Unity RAID configuration

Question 1

What RAID types can we use for Unity? Can we apply the RAID rule to all the tiers (SAS/NL-SAS/SSD)? Or the rule is different and depends on the tier?

Answer

We can use below RAID types.

The RAID rule does not depend on its tier. We can apply the same rule to all the tiers (SAS/NL-SAS/SSD).

Question 2

Do we have to choose exactly the same RAID configuration when adding disks into an existing pool? For example, can we add 4+1 RAID5 into an existing 8+1 RAID5 pool?

Answer

No, you don’t have to choose exactly the same RAID configuration. You can add 4+1 RAID 5 into an existing 8+1 RAID5 pool.

Below is an example of adding 4+1 RAID5 into an existing 8+1 RAID5 pool.

Question 3

I found we could choose only pre-set disk numbers (=Supported Configuration) in Unisphere GUI when adding disks into a pool.  Can we flexibly choose any number of disks when configuring RAID by Unisphere CLI? For example, can we configure 5+1 RAID?

Answer

No, we can’t. We have to choose “Supported Configurations” number of disks.

I tried to create 5+1 RAID but could not make it (as follows).

>uemcli -d xxx.xxx.xxx.xxx -u admin -p xxxxxxxxxxx/stor/config/pool -id pool_7 extend -diskGroup dg_16 -drivesNumber 6

Storage system address: xxx.xxx.xxx.xxx

Storage system port: 443

HTTPS connection

Operation failed. Error code: 0x6700171

The wrong number of disks was supplied for the specified RAID configuration, or the number of disks did not match the default RAID configuration for the drives in the disk group. (Error Code:0x6700171)

[FYI] I could, of course, create 4+1 RAID.

>uemcli -d xxx.xxx.xxx.xxx -u admin -p xxxxxxxxxxx/stor/config/pool -id pool_7 extend -diskGroup dg_16 -drivesNumber 5

Storage system address: xxx.xxx.xxx.xxx

Storage system port: 443

HTTPS connection

Operation completed successfully.

The original content is https://community.emc.com/thread/230154 (written in Japanese)

                                                                                                                                              

Author: Yutaro