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Kirk J
Cisco Employee
Cisco Employee

Introduction

This guide is to provide example steps via the CIMC Web interface on how expand a Virtual Drive (VD) by adding additional physical drives.

Requirements:

  • UCS C series M4 generation server
  • 2.0(10) or higher CIMC firmware version
  • 12Gb LSI raid controller
  • Drives being added are same technology (i.e. HDD, SSD, SAS, SATA, 4K, 512B Sector)
  • Drives being added are same or larger capacity.
  • ALWAYS make sure you have valid backups of data before attempting raid volume modifications such as this.

Adding Drives to an existing Virtual Drive

Login to CIMC web interface.

Click on Storage Tab.

Select the 12Gb SAS Raid controller in left pane (under Storage Tab).

Confirm you have some available unused drives with the 'Unconfigured Good' status.

In the right pane, click on Virtual Drive Info, and select the raid volume (Virtual Drive Number).

Click on 'Edit Virtual Drive', then 'OK' when prompted about taking a backup of your data.

You now have the option to Select the same raid level (RAID 5 in my example), or you could chose a valid raid level to migrate to.

After selecting the RAID level, you are then prompted to select the physical drives to add.  Drives in any configuration other than 'Unconfigured Good' will not show up in the list. 

You can also note or adjust the 'Write Policy' and 'Read Policy' that is set.  If you are using non-SSD harddrives, then you generally want the Write policy to be set to 'Write Back Good BBU' and Read Policy set to 'Always Read Ahead'.

Click 'Save Changes'

 

You will now see Operation Status show Reconstruction in Progress with a percentage counter.

After a bit, you will likely see the virtual drive show a degraded state/cache Degraded while the rebuild is in progress.

The virtual drive size, and list of physical drives, will not update until the reconstruction and background init complete.

If you are doing the expansion while the server is booted/running a work load, this may take a long time to complete.

When I have tested drive expansions, it took around 4-5 hours adding 2 additional drives to an existing 3 drive RAID 5, (total 5 drives) with the server at the BIOS setup screen (to avoid booting).

Caveats to be aware of:

  • Best to not boot OS if you are expanding the VD that is your boot VD, until reconstruction is complete.
  • Don't expand your Boot VD to or past 2TB in size, or you will have to deal with complications of needing a GPT partition, and setting up UEFI boot.  This may require a reinstall of the OS in some cases.
  • You will need to expand your partitions within your OS (or create additional ones) in order to utilize the additional space.

Comments
Lillian Phyo
Level 1
Level 1

Dear Mr Kirk J, I have to expend 2TB x 2 harddisk to 24TB existing ucs. Let me know this procedure can cause any data lost while i expend like this?

Kirk J
Cisco Employee
Cisco Employee

In my opinion, one of the reasons you generally don't see non-destructive physical drive expansion in official Cisco docs or Raid config guides, is that there are just too many unknown variables in customer environments that can cause the process to go wrong.

A couple of years ago, I started posting some forum level 'How to' expansion docs because customers kept asking.

I have had many test scenarios in the Lab work just fine.

As my previous posts note, here are some common requirements:

  • Don't expand an existing VD that is your boot volume, in legacy/BIOS mode past 2TB.  Going past 2TB requires UEFI boot config, a GPT partition instead of a MBR, etc.
  • Don't mix & match drive types (i.e. SAS & SATA), or 512 and 4Kn sector size drives in same raid volume/VD
  • Plan on the process taking a WHILE. 
  • It is best to leave the server at the F2 BIOS setup screen so the OS is not booted, causing competing controller and disk I/O with the reconstruction process that is running.
  • Understand the process of how your OS's file systems will expand the additional space (i.e. Linux LVM expansion, ESXI- adding extents, etc)
  • Have ROCK solid reliable Power.  Power interruptions during this process will be lethal to your raid volume.
  • Most importantly, Backup, Backups, Backups.  Make sure you have some level of backs that you can use in the event you had to recreate the raid volume from scratch, reinstall the OS & Apps, and restore data.

 

Please list your exact config you have now, and what you are planning on going to?

(for example, Raid 5 with qty 4 2TB disks going to Raid5 with qty 10 2TB disks)

 

Thanks,

Kirk...

Harry E
Level 1
Level 1

Dear @Kirk J, I'm following your guide above, but although I have 8 new disks available as 'unconfigured good', 20220921_215106-Remote Desktop Manager Free [S1DE3009].jpgwhen editing an existing VD, the drop down for selecting the RAID level gives me no options!

20220921_214817-Remote Desktop Manager Free [S1DE3009].jpg

How can I add disks to this VD? 

Thanks,

Harry

Harry E
Level 1
Level 1

And the answer is ... you cannot add disks, if there are more than two VDs present on the raid group:

 

20220924_100534-Slack _ Search Results _ NTS.jpg

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