LeftHand is not just iSCSI

About a year ago, the LeftHand disk array, developed by the company of the same name, which HP acquired in 2008, appeared in the HP product portfolio of storage systems.

Typically, LeftHand products are considered just as entry-level disk arrays designed for iSCSI-based SANs. However, the LeftHand developments, which are now officially called the HP StorageWorks P4000 , stand out from other systems by implementing a number of advanced data protection functions, some of which were only recently found in high-end disk arrays.

Before talking about the benefits of the StorageWorks P4000 functionality, it makes sense to briefly describe its architecture. The P4000 system is built from storage modules (essentially a rack-mount dual-processor server of the standard HP ProLiant architecture with redundant power supplies and fans), each of which is equipped with a storage controller, two network single or optional ten-gigabit Ethernet cards, a RAID controller and, of course, rigid MDL SAS drives. Storage modules are running a specialized SAN / iQ operating system.

Through the Ethernet network via iSCSI protocol, these modules are connected to a cluster, and their resources (disks, RAM, network interfaces, cache memory) are combined into a common pool. For fault tolerance of the connection between cluster nodes, you can also reserve Ethernet network connections, since, as mentioned above, each node has two network cards. In a StorageWorks P4000 cluster, you can create disk volumes that consist of drives that are physically installed in different nodes. Cluster management is performed using the Centralized Management Console (CMC), which is installed on a Windows or Linux computer connected to the iSCSI SAN.

So, let's see what a cluster of P4000 storage modules can do under SAN / iQ management with pooled resources:

• storage capacity is scaled horizontally by adding a new StorageWorks P4000 module to the cluster. This operation is performed in hot mode and SAN / iQ automatically expands volumes to the disks of the new module (to reduce the load on the network when changing the volume configuration in SAN / iQ, the Bandwidth throttling traffic adjustment function is used). In addition, nodes can be excluded from the cluster online;
• StorageWorks P4000 supports tiered storage - for example, you can create a volume whose data is stored on fast and expensive SAS disks, and when this data is outdated, move it to SATA disks on another module. Moving a volume between physical disks and changing the configuration of a SAN / iQ volume is done automatically - the system administrator does not need to manually migrate the data and re-define the volume configuration;
• function Network RAID in SAN / iQ allows you to build a distributed RAID-array of drives installed in different modules StorageWorks P4000. In the first version, Network RAID only supported RAID level 1, i.e. disks of different modules could be mirrored among themselves, but the new version of StorageWorks P4000 G2, which was released earlier this year, already supports RAID levels 5 and 6, therefore, it is possible to provide more economical (in terms of overhead for useful capacity) data duplication . Network RAID allows you to combine storage modules installed at different sites into a disaster-proof distributed RAID array;
• SAN / iQ implements the function of dynamic capacity allocation Thin Provisioning , i.e. if the physical capacity allocated to that is used up, then you can give it additional disks online. Thin Provisioning reduces the cost of purchasing drives - the customer does not need to buy capacity for future use;
• instant cloning of Smart Clone volumes - system images are saved and then only the changes are copied, but not the data itself. Such cloning is very convenient for working with production data when developing and testing new versions of application software and loading server OSs via SAN;
• snapshots SnapShot - significantly simplify the backup and recovery of data, including the use of remote copy function the Remote the Copy ;

All of these functions are included in the standard configuration of StorageWorks P4000 G2 and the owners of these systems do not have to spend money on purchasing software licenses (unlike buyers of high-end and middle-class disk systems). In addition, SAN / iQ can run on any server with a standard architecture; therefore, HP also supplies this OS as a separate P4000 VSA Software product for building an iSCSI storage system on the x86 server hardware platform.

As always, we will be happy to answer your questions and hear your feedback if you have already worked with the P4000 line or LeftHand products.