Storage Arrays come in all sorts of shapes and sizes. At the consumer and small business end there are external storage devices which don’t even qualify as storage arrays. These are individual external drives, and generally should not be utilized because they lack RAID. Though with a good backup plan they can be feasible. Iomega and Buffalo are two popular makers of these sort of drives and Iomega’s External Hard Drive section on their website is a good place to start browsing for these items, though Iomega is significantly more expensive than Buffalo Technologies for not that much more in terms of performance or reliability.
Small RAID Arrays
After a simple external hard drive comes redundant hard drive arrays which can be directly attached to a server or workstation. These are RAID’ed drives that usually connect through USB, Firewire, or eSATA. They can provide 1 or 2 TB of storage and may be adequate for many small businesses. Again, Iomega and Buffalo are both popular providers of this form of technology as well as LaCie.
Network Attached Storage (NAS)
Next one enters the realm of Network Attached Storage (NAS). NAS is not attached to a server or workstation, but rather exists as its own distinct entity on the network which can be accessed by the various workstations and servers on the network. On the lower consumer end are Buffalo Technology, Iomega, and other similar companies. Moving higher up the food chain one will find offerings from Dell and HP.
Direct Attached Storage (DAS)
Another technology that is popular is Direct Attached Storage (DAS). In the past this was usually connected via SCSI cable but has recently been replaced by SAS cabling. Examples of this technology include the Modular Storage Arrays from HP and PowerVault’s and MD1000 arrays from Dell. These devices attach directly to a server, greatly expanding the capacity of the server and can be used to create NAS’s.
Storage Area Networks (SAN)
There are also Storage Area Networks (SANs) which are at the higher end of the cost range but offer some performance benefits. In the past these SANs where created using fibre channel (fc), an extremely expensive methodology. This more recently is being supplanted at the mid-level by iSCSI – a method that uses existing LAN network cabling to move data across the network and is much more economical. Fibre Channel cables run from the individual server to a fibre channel switch and then into the various storage arrays. To add more capacity one adds more arrays to the switch. With iSCSI the need for the switch is done away with, as well as the expensive fibre channel cards that are required for each server. Overall, the reasons to move to a FC SAN are steadily decreasing unless one already has the architecture in place. Good examples of iSCSI SAN technology include EqualLogic’s products. EMC offers both FC and iSCSI SANs.
SATA, SCSI, or SAS?
There are three main drive technologies currently available to businesses besides Fibre Channel. The first is SATA. SATA is the slowest of the three technologies and generally operates at 7200 RPM (rotations per minute). It is still more than adequate for many small businesses. If you are using your storage for in office hosting you will be fine with SATA. If you are hosting mainly static information that is not changed or accessed frequently simultaneously then you will also probably be fine with SATA. It also happens to be the least expensive.
The next technology is SCSI. SCSI was the technology of choice until recently, but within the last several years it has been being rapidly replaced by SAS, a technology which combines the best of SATA with SCSI. At this point there is little use in utilizing SCSI and one would do better to purchase SAS based technology. SCSI is fast but it is also quickly becoming outdated.
The final technology is SAS, a relatively new technology that has been taking the industry by storm. It is the best option for companies that need fast drives. Fast drives are needed when you have a highly utilized database server, files which are constantly accessed by numerous users, etc. One of the nice features of SAS is that it is also compatible with SATA. So, if you purchase a SAS storage array and don’t initially need high speeds you can populate it with SATA drives and when you need better speeds you just pop out the SATA and pop in SAS.
- If you are a small business looking for internal storage you will probably want a tower or rack mount NAS. As mentioned above Buffalo Technologies, Iomega, and LaCie are good examples of vendors of this lower-end technology. Dell also offers some technology of this type.
- If you are looking for more robust, larger (than 3 TB) storage you will probably want to look at NAS and iSCSI SAN solutions. Some vendors worth investigating are Dell, HP, EMC, and EqualLogic. NAS devices can scale well to 50 TB with SATA, perhaps 30-40 TB with SCSI, and perhaps a little less with SAS. These limits continue to increase as prices drop and more data can be packed into the same 3.5″ or 2.5″ frame.
- I personally find the price point of HP’s Modular Storage Array’s extremely attractive. I recommend the MSA 60 because it can utilize both SATA and SAS and uses a SAS cable to connect to the NAS server, which is a bit neater and smaller than a SCSI cable.