LINBIT® offers a competitive enterprise storage solution based on DRBD® that shows that it doesn’t always have to be SAN. Storage Area Network (SAN) is the magic word for safe storage solutions. However, as SANs are based on Fibre Channel (FC) hardware, they usually are expensive due to the need for special hardware and switch components as well as fibre channel cables.
We developed a competitive alternative that combines standard storage hardware with the ethernet standard. Despite the excellent cost/performance ratio, this ethernet-based technology and the iSCSI-technology even provide you with a better storage bandwidth (10 Gbit/s) than Fibre Channel (4 Gbit/s).
Asynchronous Mirroring vs Synchronous Mirroring
Established SAN solutions require installing special fibre channel cables to connect the storage and productive systems. For security reasons, the locations of these systems should be as far away from each other as possible, making even the cable installation very expensive. For example, EMC as a provider of data mirroring, explicitly asks for a single fibre cable, a so-called dark fibre. No one uses this fibre for anything but mirroring. At least, EMC offers a redundant SAN that way – other companies don’t even have redundancy in their portfolio. Other providers only offer asynchronous mirroring instead of synchronous mirroring.
Philipp Reisner, LINBIT CTO, says, “Because the data transfer drags behind in such setups, there is always the danger that after a failure, not all data is available any more, uncovering the disadvantages of such installations.”
DRBD’s Independent Model
Reisner created DRBD. Hundreds of thousands of high-availability solutions worldwide enhanced his high-availability concept for the storage area. Large companies entirely, too. In open competitive bidding, LINBIT runs against prominent SAN specialists more and more often. While these players offer expensive hardware with just as expensive service contracts, LINBIT, based on its intelligent solution, can extend storage servers with each and every piece of hardware and is entirely independent of the hardware provider.
The annual growth of the data volume can be between 30 to 50 per cent. This means that operators must upgrade the servers on a regular base. Thanks to LINBIT, such upgrades can be done with every available piece of hardware at any time, which is the most essential factor, without interrupting the service. That even applies to all maintenance work that needs to be done. Operators must remove non-redundant SAN solutions from service during maintenance. The iSCSI Storage Area Networks by LINBIT can undergo maintenance during regular operation. DRBD redirects all recent jobs automatically to the redundant server so end-users can continue their work without interruption.
Competitive Enterprise Storage Solution
LIBINT implemented SAN on the base of the IP protocol. We did so without Fibre Channel and the expensive components needed for it. The LINBIT solution works over standard ethernet cables. A server cluster with DRBD supersedes the expensive storage box needed for fibre channels. The storage and production servers are connected via standard NICs and the iSCSI-protocol (iSCSI meaning ‘Internet Small Computer System Interface’).
DRBD does the synchronous mirroring. Even the switches are laid-out for redundancy. If an FC connection between two locations fails, the mirroring is interrupted, but the users continue to have access to the servers. When the broken network component is exchanged, the replication starts again once. If a server crashes, users can continue to work with the remaining servers – these changes are even done transparently. In cases where just a single disk crashes, all processes can be conducted on redundant disks.
“Those who want to consolidate dozens of hard disks in a single SAN storage box have had to invest loads of money into quite a lot of hardware so far, accepting huge costs for reliability. With iSCSI and DRBD, we can now offer an alternative that is ten times less expensive”, summarizes Philipp Reisner, the advantages of the Linux-based solution.
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