Launched in January, EMC’s Clariion AX4 storage system is aimed at small and medium-sized business and enterprise branch office IT managers who want to rationalise their storage infrastructures and set up an easily manageable storage system for archiving and disaster recovery.

Firms can choose from a range of connectivity options. Those wishing to integrate using standard Gigabit Ethernet switching over copper can use the iSCSI version of the AX4, while those having fast optical fibre connections may wish to deploy an AX4 with 4Gbit/s Fibre Channel (FC) connectivity.

EMC supports HP-UX, IBM-AIX, Linux, Netware, Solaris, VMware, Windows 2000 Server, and Windows Server 2003 operating systems, and the AX4 can also be accessed through VMware’s VMotion, VMware HA and Site Recovery packages.

The AX4 array hard disks can be either high-performance Serial Attached SCSI (SAS) devices or lower cost, higher capacity Serial ATA-II (Sata-II) drives. The 15,000rpm SAS drives come in 146GB and 400GB versions, while the 10,000rpm Sata-II drives are available in 400GB, 750GB and 1TB versions.

IT Week’s review system consisted of one 2U iSCSI version of the AX4, called a disk array enclosure (DAE), which had 12 146GB SAS drives, and a single 2U AX4 FC version, called a disk processor enclosure (DPE), which had 12 drives consisting of six 146GB SAS drives and six 750GB Sata-II drives. With its ability to support both SAS and Sata-II drives in the same enclosure, the AX4 enables firms to create two-tier storage architectures where frequently used data can be stored on the higher performing SAS drives and less important data on the Sata-II drives.

Both DAE and DPE had dual storage controllers, and these are hot swappable, as are the disk drives, power supplies, fans and standby power supplies. The DAE had two management network ports and four iSCSI ports, and was connected to the DPE through two 4Gbit/s FC connections.

We also had a single 1U standby power supply that we connected to the DAE through a modem link. The maximum number of drives that can be used in the array is 60, so if the new 1TB drives are used, five AX4 arrays can be stacked together to give a maximum capacity of 60TB.

For our test, we attached two standard Intel servers, each fitted with two 3.2GHz Intel Xeon dual-core processors and 2GB of system memory, with one running Windows Server 2003 R2 Enterprise Edition and the other Windows 2000 Server. Up to 64 hosts can be defined to access the array and these can be physical systems or virtual machines (VMs) running under VMware.

We connected the iSCSI ports to our gigabit switch and ran the EMC Navisphere Storage System Initialisation Wizard to define IP addresses for the disk array management and iSCSI ports. After this we could browse to one of these addresses and manage the arrays using EMC’s browser-based Navisphere Express Management Utility.

Troubleshooting
First, we set up an SMTP email server so that when the AX4 detected problems with the system, we received emails detailing the nature of the incident. We could also set up Simple Network Management Protocol (SNMP) traps, and have diagnostic files for each storage processor sent to EMC’s product support for further analysis.
We then defined “hot spare” SAS and Sata-II disks that would take over from any disk that failed during our review. Next we defined disk pools that could be assigned specific Raid properties. With the AX4, users can define Raid 1/0, Raid 3 or Raid 5 type arrays.

System access to AX4 storage requires the creation of so-called virtual disks. These are assigned to specific systems, which can then access the storage directly. Using storage from the disk pools, we created three virtual disks. Initialisation of these virtual disks was the most time-consuming aspect of setting up the AX4.

Once initialised, we could then assign these disks to our test servers, and then use the Navisphere Server Utility to allow iSCSI connectivity between the AX4 and our test servers, by “registering” our server with the AX4.

We could then move our SQL Server database onto the AX4 and copies of the various VM operating systems used on other systems in the lab. To further protect our data we could use the snapshot feature on EMC’s Navisphere Express package to give an exact point-in-time copy of the virtual disk. These snapshots could be run anytime, but would normally be run after any significant change in the datasets stored on the AX4.

To sum up, the AX4 is a solid system for firms needing to consolidate storage, or protect critical data. It allows a fair amount of expansion and is simple to set up and manage, but storage has to be allocated manually.