We have posted two blogs (1) (2) to discuss DELL NFS Storage Solution with High Availability (NSS-HA) in the past. This article introduces a new configuration of DELL NSS-HA solution which is able to support larger storage capacities (> 100 TB) compared to the previous configurations of NSS-HA.

Dell gets the support from Red Hat for XFS capacities greater than a 100 Terabytes . Details on the work that was done to get this exception for Dell is in the blog post: Dell support for XFS greater than 100 TB.

 

As the design principles and goals for this configuration remain the same as previous Dell NSS-HA configurations, we will only describe the difference between this configuration and the previous configurations. For complete details, please refer to our white papers titled “Dell HPC NFS Storage Solution High Availability Configurations, Version 1.1.” and “Dell HPC NFS Storage Solution High Availability Configurations with Large Capacities, Version 2.1.”

Storage density

In previous configurations of NSS-HA (1), each storage enclosure was equipped with 12 3.5” 2TB NL-SAS disk drives. The larger capacity 3TB disk drives are a new component in the current configuration. The storage arrays in the solution, Dell PowerVault MD3200 and PowerVault MD1200 expansion arrays are the same as in the previous version of the solution but with updated firmware. The higher capacity 3TB disks now allow higher storage densities in the same rack space. Table 1 provides information on new capacity configurations possible with the 3TB drives. This table is not a complete list of options; intermediate capacities are available as well.

Storage configuration

In previous configurations of NSS-HA, the file system had a maximum of four virtual disks. A Linux physical volume was created on each virtual disk. The physical volumes (PV) were grouped together into a Linux volume group and a Linux logical volume was created on the volume group. The XFS file system was created on this logical volume.

With this configuration, if more than four virtual disks are deployed, the Linux logical volume (LV) is extended, in groups of four, to include the additional PVs. In other words, groups of four virtual disks are concatenated together to create the file system. Data is striped across each set of four virtual disks. However it is possible to create users and directories such that different data streams go to different parts of the array and thus ensure that the entire storage array is utilized at the same time. The configuration is shown in Figure 1 for a 144TB configuration and a 288TB configuration.

Red Hat High Availability Add-On

Red Hat High Availability Add-On is a key component for constructing a HA cluster. In previous configurations of NSS-HA, the add-on used is distributed with RHEL 5.5. With this release, the version distributed with RHEL6.1 is adopted. There are significant changes in the HA design between the previous RHEL 5.5 release and the new RHEL 6.1 release. New and updated instructions to configure the HA cluster with RHEL 6.1 are listed in the appendix A of our white paper “Dell HPC NFS Storage Solution High Availability Configurations with Large Capacities, Version 2.1.

Red Hat Scalable File System package

In previous configurations of NSS-HA, the version of XFS is 2.10.2-7 which is distributed with RHEL 5.5. In the current version of NSS-HA, the version of XFS used is 3.1.1-4 and is distributed with RHEL 6.1. The most important feature of the current XFS for users is that it is able to support greater than a 100 Terabytes of storage capacity.

Summary of changes

Table 2 lists the similarities and difference in storage components. Table 3 lists the similarities and differences in the NFS servers.

Dell NSS-HA solution provides a high availability and high performance storage service to high performance computing clusters via an InfiniBand or 10Gigabit Ethernet network. Performance characterization of this version on the solution is described in “Dell HPC NFS Storage Solution High Availability Configurations with Large Capacities, Version 2.1.” Additionally, in our next few blogs, we will discuss the performance of the random and metadata tests on 10GbE and other performance related topics.

By Xin Chen and Garima Kochhar 

 References

1.  Dell NFS Storage Solution with High Availability - an overview

http://en.community.dell.com/techcenter/high-performance-computing/b/hpc_storage_and_file_systems/archive/2011/07/24/dell-nfs-storage-solution-with-high-availability-an-overview.aspx

2.  Dell NFS Storage Solution with High Availability – XL configuration

http://en.community.dell.com/techcenter/high-performance-computing/b/hpc_storage_and_file_systems/archive/2011/08/04/dell-nfs-storage-solution-with-high-availability-xl-configuration.aspx

3.  Red Hat Enterprise Linux 6 Cluster Administration -- Configuring and Managing the High Availability Add-On.

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/pdf/Cluster_Administration/Red_Hat_Enterprise_Linux-6-Cluster_Administration-en-US.pdf

4.  Dell HPC NFS Storage Solution High Availability Configurations, Version 1.1

http://i.dell.com/sites/content/business/solutions/whitepapers/en/Documents/dell-hpc-nssha-sg.pdf