UCCX Hard Disk Requirements

[bradburyh]

I have a question from a customer on the hard disk requirements for the UCCX 300 and 400 users deployments.  He is questioning why in a UCS B-series environment using SAN storage is mirroring of the OS required as it is redundant and a waste of space in a VM environment.  He was looking to find a way to opt out of this.  I know that if hardware specifications are not met the typical UC application will not install and have told him we need to be careful in meeting all specifications.  But does anyone have any idea as to why this is done this way for UCCX.  None of the other applications seem to mention using mirroring.

[Hermanus Janse van Vuuren]

Please see the following PDF with regards to the HDD sizes

http://www.cisco.com/en/US/docs/solutions/CVD/Aug2013/CVD-HelpDeskUsingCiscoUCCXDesignGuide-AUG13.pdf



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[bradburyh]

I understand the requirements.  I know that the UCCX 400 agent OVA template requires 2 146GB HD disks.  My questions is to understand why this requirement, when according to the Virtualization wiki Disk2 is only used for mirroring.

http://docwiki.cisco.com/wiki/Virtualization_for_Cisco_Unified_Contact_Center_Express#Notes_on_400_agents_VM_configuration

"vDisk 1 = Operating System and Unified CCX binaries vDisk 2 = RAID 1 mirror will be setup between vDisk 1 and vDisk 2"

This seems like a huge waste of disk space in a VM environment using the UCS chassis when there is already a RAID set-up at the VM/SAN level.  This was the concern my customer had.  The OS configuring a RAID is redundant and wastes SAN disk space.

[Hermanus Janse van Vuuren]

Hi,

Sorry if I have miss read your question.

All I can gather is the mirroring has to to with HA and best practise on VM ware according to cisco:

Best Practices for Storage Array LUNs for Unified Communications Applications

There are various ways to create partitions or Logical Unit Numbers  (LUNs) in the storage array to meet the IOPS requirement for Cisco  Unified Communications applications (see IO Operations Per Second (IOPS)}.

The best practices mentioned below are meant only to provide  guidelines. Data Center storage administrators should carefully consider  these best practices and adjust them based on their specific data  center network, latency, and high availability requirements.

The storage array Hard Disk Drive (HDD) must be a Fibre Channel  (FC) class HDD. These hard drives could vary in size. The current most  popular HDD (spindle) sizes are:

• 450 GB, 15K revolutions per minute (RPM) FC HDD
• 300 GB, 15K RPM FC HDD

Both types of HDD provide approximately 180 IOPS. Regardless of the  hard drive size used, it is important to try to balance IOPS load and  disk space usage.

LUN size must be less than 2 terabytes (TB) for the virtual  machine file system to recognize it. For Cisco Unified Communications  virtual applications, the recommendation is to create a LUN size of  between 500 GB and 1.5 TB, depending on the size of the disk and RAID  group type used. Also as a best practice, select the LUN size so that  the number of Unified Communications virtual machines per LUN is between  4 and 8. Do not allocate more than eight virtual machines (VMs) per LUN  or datastore. The total size of all Virtual Machines (where total size =  VM disk + RAM copy) must not exceed 90% of the capacity of a datastore.

LUN filesystem type must be VMFS. Raw Device Mapping (RDM) is not supported.

The following example illustrates an example of these best practices for UC:

For example, assume RAID5 (4+1) is selected for a storage array  containing five 450 GB, 15K RPM drives (HDDs) in a single RAID group.  This creates a total RAID5 array size of approximately 1.4 TB usable  space. This is lower than the total aggregate disk drive storage space  provided by the five 450 GB drives (2.25 TB). This is to be expected  because some of the drive space will be used for array creation and  almost an entire drive of data will be used for RAID5 striping.

Next, assume two LUNs of approximately 720 GB each are created to  store Unified Communications application virtual machines. For this  example, between one and three LUNs per RAID group could be created  based on need. Creating more than three LUNs per RAID group would  violate the previously mentioned recommendation of a LUN size of between  500 GB and 1.5 TB.

A RAID group with RAID 1+0 scheme would also be valid for this  example and in fact in some cases could provide better IOPS performance  and high availability when compared to a RAID 5 scheme.

The above example of storage array design should be altered based  on your specific Unified Communications application IOPS requirements.

Below is a graphic of an example configuration following these  best practices guidelines, note there are other designs possible.