NCDA Study Part 2.4 – Data ONTAP: Configuration

As always download the newest version of the blueprint breakdown from here.

This section pertains to RAID groups within Data ONTAP.  RAID groups consist of the physical disks within the shelves of the NetApp system.   Data ONTAP supports three different types of RAID groups, but only two natively.  RAID4 and RAID-DP are the two natively supported RAID types and are the ones most commonly run into.  Data ONTAP is capable of supporting RAID 0, but that’s only on third party types of storage and the RAID level isn’t truly protected by Data ONTAP but by the underlying storage array.  Data ONTAP simply uses RAID0 for all the third party arrays.  While RAID0 provides no protection on the Data ONTAP side, resiliency can be achieved by the underlying storage controller.  For this section, we’ll be concentrating on RAID4 and RAID-DP and their configuration.

Since RAID groups are components of an aggregate and plex, and to create one you have to do it at the aggregate level, refer back to this post on how to create a standard RAID4 and RAID-DP RAID group.  In this post I’m going to dig a bit deeper and do some other labs.

***Remember that RAID Group sizes differ based on disk type and the model type of the NetApp device.  In our case below we’re not pushing the limits on RAID Group size maximums but it’s an important concept to remember.  You should always attempt to create equalized RAID Groups if you need more than one.  This helps with performance.  Also, I’m not taking into consideration the best practice in regard to hot spare drives.  You’ll notice a few error messages when you add disks and don’t take spares into consideration.  Here they can be ignored, in the real world you need to think about what you’re doing in that regard.  Here is a link to a good thread about those practices and how many you should use per disk type in your array (refer to Tip#2 although the entire article is great).  ***

We’re going to perform the following labs in both the CLI and System Manager where the capabilities to do in both exist.

  • Add RAID4 group to existing aggregate
  • Add RAID-DP group to existing aggregate
  • Expand RAID Group
  • Add Disks to RAID Group
    • Single Disk
    • Specific Disk

Add RAID4 group to existing aggregate – CLI

The first step is determining the free spare disks that are available to be added to the RAID group.  This can be done using two different commands:

aggr status –r
sysconfig –r

cli_raid4_rg_add_step1

We have 7 spare disks that we can use to create a new RAID group and add it to ‘newaggr’.  To do this we perform the following commands to create a new RAID group, add the remaining 7 disks, preview what the RAID groups will look like and then create it:

aggr add newaggr –g new –T FCAL 7

cli_raid4_rg_add_step2

Add RAID-DP group to existing aggregate – CLI

This process is the exact same as above, however the only difference is that RAID-DP will use two disks for parity and double-parity.

The first step is determining the free spare disks that are available to be added to the RAID group.  This can be done using two different commands:

aggr status –r
sysconfig –r

cli_raiddp_rg_add_step1We have 7 spare disks that we can use to create a new RAID group and add it to ‘newaggr’.  To do this we perform the following commands to create a new RAID group, add the remaining 7 disks, preview what the RAID groups will look like and then create it:

aggr add newaggr –g new –T FCAL 7

cli_raiddp_rg_add_step2Add RAID4/RAID-DP group to existing aggregate – System Manager

I combined both RAID4 and RAID-DP because you have no control over setting the RAID group type when adding a new group anyway.  If you add a new group, it will always be the same type as rg0 because all RAID Groups must be the same size.    You can however only have a RAID Group that is sized for 7 disks, composed of 4 disks.  This is not optimized but is possible.  Either way, both ways are exactly the same.  When adding new RAID groups and disks via System Manager, it will halt you when you try to use all the disks without leaving a hot spare.  In this case we can’t add all the disks and keep the RAID groups the same size.  So we’ll just add 6 disks instead.  As long as we’re aware of the spares concern and the RAID group size concern, this isn’t an issue and still accomplishes what we’re trying to do for studying purposes.

There are actually two ways you can add a new RAID group and disk using System Manager.  The first way is really Data ONTAP doing it for you and the second way is really how you do it.  I’ll show both ways.

First way (automatic way) – This technically isn’t adding a RAID group in the sense that you’re actually performing the adding functionality, however it will add a RAID group for you.  The default behavior of adding disks to a RAID group is this; if a RAID group is sized larger than the amount of disks it is currently composed of, it will add any new disks to attempt to fill that group first.  If that group is already full, it will create another group automatically.  This is both good and bad because we want to try and keep our RAID group sizes as equal as possible.  You could end up with a group that is sized to 16 and a new group sized to 6 disks.  This could bring about performance problems.  So don’t use this first way if you are unsure of your RAID group size.  Once you add disks to a RAID group, you can’t take them out without destroying the aggregate first.  Be careful!  The ‘newaggr’ aggregate was built with a RAID group size of 7 disks.  Since it’s already composed of 7 disks, adding more disks to the aggregate will create a new RAID group.

Open and connect to the Data ONTAP device, expand the device, Storage, click on Disks

osm_rg_add_fw_step1From this screen you will be able to see the disks and how they are marked by ‘State’.  We’re looking for disks marked ‘Spare’.  Using the CTRL key, highlight 6 spare disks and click ‘Add to Aggregate’.  You can’t add all 7 because you will get the hot spare warning.

osm_rg_add_fw_step2Select the aggregate, ‘newaggr’ and click the ‘Add’ button.  This will add the disks.  You can verify this by clicking on the Aggregate option on the left, click on ‘newaggr’ and then selecting the ‘Disk Layout’ tab at the bottom.  You should now see two RAID groups, rg0 and rg1.  You will also notice the disk count is now 13.

osm_rg_add_fw_step3Second way (the advanced way) – This is a much more advanced way and has more customizable way to actually add a RAID group to an existing aggregate.

Open and connect to the Data ONTAP device, expand the device, Storage, Aggregates and click on ‘Add Disks’.

Click on the ‘Advanced’ option to expose the RAID Group configuration.  The key here is the RAID Group size and the ‘Add Disks To’ option.  In this shot the size is 7 and the option is to add disks to existing groups first, then Data ONTAP will create a new RAID Group if those are full.

osm_rg_add_rw_step1Click on ‘Select Disks’ and add 6 disks.  Remember that System Manager will give you a hard time about spares so you can only add 6 for now.  It’s not a big deal and still completes what we’re trying to accomplish.

osm_rg_add_rw_step2You’ll get the typical warning about the groups being unbalanced, but again you can ignore this message.

osm_rg_add_rw_step3Clicking on ‘Add’ will commit the changes and add the disks.  Now we can verify that it worked.  You should see 13 disks in the aggregate and two RAID Groups in the disk layout tab.

osm_rg_add_rw_step4You can only expand or re-size RAID Groups on a per-aggregate basis.  You cannot change the size of only one RAID Group in an aggregate unless the aggregate is composed of only one aggregate.  If it’s composed of two groups, you’ll be changing the size of both groups because all RAID Groups must be the same size.

Expand RAID Group – CLI

I started with two group 5 disk RAID Group setup and I’m going to expand them to 6 disks.  We can verify this by running the following command:

aggr status –r

cli_expand_rg_step1As you can see we have two 5 disk groups.  You won’t get a confirmation or any indication that the size actually changed unless you run both commands below.  One actually performs the operation and the other confirms the change.  Now we’re going to expand to 6 disks with the following command:

aggr options newaggr raidsize 6
aggr status

cli_expand_rg_step2Add Disks – Single – CLI

To add a disk to a RAID Group you must first take a look at the size of the group and how many disks are already assigned.  The following commands will verify the size of the group and show how many are there already.

aggr status
aggr status –r

cli_add_disks_rg_step1I cut out unnecessary output from the commands.  We can now understand that we have two RAID groups, they are 6 disks in size and they only have 5 disks in each group.  If we want to add a single disk to rg0, we simply run the following commands to add and verify:

aggr add newaggr –g rg0 –T FCAL 1
aggr status –r

cli_add_disks_rg_step2We can now see that the disk addition was completed and that rg0 now has 6 disks in its group and rg1 only has 5.

Add Disks – Specific – CLI

Now we’re going to add a specific spare disk from the spare pool to rg1 to bring it up to 6 disks in its group.  Looking at the following command we’re going to add spare disk v5.28 to rg1:

aggr status –r

cli_add_disks_rg_specific_step1We can see that v5.28 is free in the spare list so we can add it by running the following command and verify:

aggr add newaggr –g rg1 –d v5.28
aggr status –r

cli_add_disks_rg_specific_step2Add Disks – Single – System Manager

Open and connect to the Data ONTAP device, expand the device, Storage, Aggregates and click on ‘Add Disks’.  Click on the ‘Select Disks’ option and put in a single disk.

osm_add_disks_rg_step1Click ‘OK’ and then ‘Add’ to commit the changes.  Verify the changes.

osm_add_disks_rg_step2Add Disks – Specific – System Manager

To do a specific disk, you need to go into the Disks area that I talked about before.  While above I stated you could add a new RAID Group automatically, this area is more specifically for adding specific disks.

Open and connect to the Data ONTAP device, expand the device, Storage, click on Disks.  Select the disk from the list and then click on the ‘Add to Aggregate’ button.

osm_add_disks_rg_specific_step1Select the name of the aggregate and verify all the information is correct.  Click on ‘Add’ and then verify the disk was properly added.

osm_add_disks_rg_specific_step2

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