Review: Riverbed brings branch office storage back to the data center

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Riverbed Granite 2.5 eliminates remote office server administration and backup pains by delivering iSCSI and Fibre Channel storage over the WAN

Usually when someone talks about "collapsing" something, images of toppling towers, imploding buildings, tumbling bridges, and other destruction come to mind. But when IT organizations are able to collapse server and storage resources back to the data center by removing hardware and admin chores from remote offices, that's a good thing.

Riverbed Technology, well known for its WAN acceleration and optimization solutions, also offers a way to collapse branch office server and storage resources back to the data center while making it seem as if those resources were still living in the remote office.

[ Riverbed Granite is an InfoWorld 2014 Technology of the Year Award winner -- read about all of the 2014 Technology of the Year Award winners. | Get the latest practical info and news with Paul Venezia's The Deep End blog and InfoWorld's Data Center newsletter. ]

Riverbed Granite 2.5 leverages a pair of appliances to "project" iSCSI and Fibre Channel LUNs from the data center to the branch, removing the burden of installing and maintaining storage from the remote office. Servers still run in the branch office, where performance remains LAN-like to users, but the virtual machines and storage volumes reside in the data center, under central IT control. Perhaps best of all, backups are no longer conducted over the WAN, but run right in the data center.

Bending space and time
Granite Core, available in the form of a physical or virtual appliance, works with iSCSI and (new in the 2.5 release) Fibre Channel and FCoE (Fibre Channel over Ethernet) SANs. Granite Edge, available only as a physical appliance, works with Granite Core to expose the data center storage to the branch office as iSCSI targets, so any server that speaks iSCSI can take advantage of Granite's acceleration. In addition to Fibre Channel support, new features in this release include a comprehensive Snapshot Manager that makes sure all data is committed to the SAN before the snapshot takes place.

One aspect that hasn't changed from previous releases is that Granite's data prefetching works only with VMFS and NTFS file systems. With VMFS and NTFS, the Granite Edge is able to predict future block requests based on past requests and prefetch the blocks from the Granite Core before the server requests them, preloading the local cache and improving performance. Granite cannot predict other file systems, like NFS and EXT3, but this is where Steelhead plays a role by optimizing and accelerating this traffic over the WAN. Once the data is in Granite Edge's cache, regardless of file system, all is well and performance is LAN-like.

Granite works best when Core and Edge can see each other without any firewalls involved, like over a VPN or MPLS. Because my lab wasn't directly connected to the Granite Core installation, I had to open a handful of ports in my firewall. This did allow my test system to work flawlessly, but in actual practice, IT will want a more secure and locked-down link between Core and Edge.

Getting your Fibre
One of Granite's newest and most interesting features is the addition of support for Fibre Channel storage arrays. Previous versions of Granite were limited to iSCSI SANs. Granite 2.5 now also exposes Fibre Channel SANs to Granite Edge, but with a caveat. A Granite Core physical appliance does not have the ability to connect natively to Fibre Channel. Instead, you will have to spin up a Core Virtual Edition appliance and connect the underlying ESXi host to the Fibre Channel storage. Because ESXi can talk to the Fibre Channel system, virtual Core sees the Fibre Channel storage in ESXi as raw disk. Core can then mount the raw disk as a LUN and project it to an Edge appliance. In a way, Granite is proxying the Fibre Channel connection through ESXi. Although this seems a bit cumbersome, it did work flawlessly in my testing.

Another improvement in Granite is Snapshot Manager, a comprehensive engine for backing up machines hosted in the branch office while keeping the backups application consistent. Granite Core initiates snapshots via VMware APIs for virtual servers and through the Riverbed Host tools plug-in for physical Windows servers.

For virtual environments, Edge tells ESXi to flush its buffers, take a snapshot, and synchronize back to Granite Core. For physical servers, the Host Tools plug-in works with the Windows VSS (Volume Shadow Copy Service) framework to quiesce the applications and flush the data to the LUN prior to the snapshot. This process guarantees that the backed-up data is consistent and ready to be backed up to nearline or offline storage. Having "application consistent" snapshots -- that is, all transactions have been committed to disk -- will be critically important if you should ever need to restore a database or mail server hosted in the branch. If the data is not application consistent, there's a very good chance that data will be corrupt.

Pin the LUN
Typically, the Granite Edge will cache a subset of each LUN made available by Granite Core. However, Granite also allows you to "pin" LUNs to the Edge appliance. Pinning is the process of storing a full copy of the LUN from the data center to the Edge. Granite keeps the copy of the LUN in the data center consistent with the pinned version in the background. Pinning works best for non-accelerated file systems, like NFS, and for applications that see a high level of I/O, such as database servers. Just keep in mind that pinning eats into local disk resources.

Riverbed's Granite is an excellent solution that, while still very new, is already very mature. When paired with Steelhead WAN acceleration, Granite delivers storage over the WAN at LAN-like speeds. Being able to keep the virtual machines and data storage in the data center greatly reduces the chance of loss and eliminates the headaches of remote administration and remote backups. If managing your branch office infrastructure has become a royal pain, take a good look at Granite.

Riverbed Granite 2.5 at a glance

 
Pros
  • Projects iSCSI and Fibre Channel LUNs to branch offices
  • Brings LAN-like performance (via prediction and block prefetching) to remote NTFS and VMFS file systems
  • Works exceedingly well over the WAN
  • Snapshot Manager quiesces branch office data prior to execution
Cons
  • Prediction and prefetching limited to VMFS and NTFS
  • Best results require a Steelhead appliance
CostGranite Core starts at $7,995; Granite Edge starts at $7,495

This article, "Review: Riverbed brings branch office storage back to the data center," was originally published at InfoWorld.com. Follow the latest developments in networking at InfoWorld.com. For the latest business technology news, follow InfoWorld.com on Twitter.

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