Rocket Storage Monthly: HDS Replication and Virtualization
Hitachi Data Systems, more commonly just HDS, is a major player in the enterprise storage system space that I’ve yet to cover in previous entries. They’ve been in the business of enterprise storage for well over a decade now and have a coherent lineup that spans the mid to high-end segments. Let’s take a look at the models and some of the backup solutions offered for HDS enterprise storage.
Currently, HDS has a few storage families within the enterprise market, such as the Hitachi Unified Storage (HUS), and Virtual Storage Platform (VSP). Despite having different families, one of the benefits of HDS is that the storage arrays work in a similar fashion as far as the end user is concerned. HDS has software such as the Command Suite and Command Control Interface, both of which support a very large selection of their storage devices going back many years. Indeed, some command reference entries for Command Suite listed variations that would be compatible with some of HDS’s earliest models, hinting at software backwards compatibility that is highly competitive.
For the current HUS and VSP models, I have not yet encountered differences in configuration or management. I find that the similarity of software management would be helpful to big businesses which may have a diverse environment of storage devices spanning mid to high end, older to brand new. The difference then between a mid-range HUS and a high end VSP is a matter of performance and extended feature set.
Local and Remote Replication
The HUS and VSP also share a common set of backup methods. For HDS enterprise storage, there are four primary backup technologies: ShadowImage, Thin Image, TrueCopy, and Universal Replicator. ShadowImage provides local full volume replication, to make copies of critical data from a point-in-time, and can be cascaded for tiers of replication. Thin Image is another local replication technology, also creating a backup from a point-in-time but in the form of a copy-after-write or copy-on-write snapshot.
TrueCopy and Universal Replicator on the other hand are remote replication and mirroring technologies. TrueCopy is synchronous and meant for closer distances (Although an async mode does exist), while Universal Replicator is asynchronous and covers extended distances. With the exception of the HUS 100 which cannot utilize Universal Replicator, these replication technologies are present on the HUS and VSP family storage systems that make up HDS’s current lineup, giving a familiar feature set across a few different price points.
V for Virtualization
One of the most interesting features of modern HDS storage is External Storage Virtualization. Businesses may find themselves getting rid of old storage arrays when upgrading to new ones as they may not play well together and have no other use for the arrays. For some arrays, purchasing multiple nodes is the only option to scale beyond the storage capacity of one array. However, the VSP lives up to the virtualization part of its name with External Storage Virtualization.
The idea of this virtualization is that legacy or low cost storage arrays may be connected to an HDS array and that HDS array will be able to access the external storage and integrate it into a storage pool. To the end user, this is just additional storage within the HDS array. Even better, this storage can still be utilized with a variety of HDS features including ShadowImage and Thin Image replication. I think this is a great feature for giving the flexibility to reuse arrays that may had otherwise gone unused or been replaced.
As with the EMC and HP storage that I’ve covered in the past, there are far more abilities to HDS arrays than can be covered in one article. However, I hope that this gives a bit of background on the replication types that can be used with HDS as these might be covered in more detail in another entry. For more information about the software support for each model, be sure to look at the software matrix from HDS’s site here. If External Storage Virtualization interests you, here’s a list of the storage devices that HDS supports.