Reliable storage is essential for every business. We examine the available options and explain the issues to check.
Putting the right tech in place for your business can be difficult if you're just trying to cover your immediate needs. When it comes to storage, you need to have an eye on the future as you deploy equipment today.
Key Issues To Consider When Buying Storage
You'd think storage is all about figuring out the capacity you need. But there's much more to it. Back in Chapter 1, we discussed how deploying a server needs some thought about the operating systems and virtualisation platform that best suits your needs. Each of those virtual servers needs access to storage space for the software and the data you create with the application.
In the old days, the server would hold all the storage. If you have several servers, it was common to end up in a situation where one server was filled to the brim with data, causing constant stress to the business as files were either moved or deleted to make room.
They could also be underutilised, making you wonder why you spent the money on capacity that you're unlikely to ever use.
In today's world, the storage is usually held centrally, in its own device. Each of the servers is allocated a portion of the storage pool. If an application needs more, it can be allocated a little more as needed.
The other advantage of this approach is that storage appliances that are used can be loaded up with enough capacity to get you by your current needs but you can add more disks when needed. Usually, this can be done without any interruption to the business.
Types of Drive
When you're looking at storage for your business, there's quite a bit jargon to negotiate.
For example, hard drives come in two main types: HDD and SSD. A HDD, ort hard disk drive, is the traditional hard drive that we've been using in computes since the 1970s. It's comprised of a series of spinning platters that are used to digitally store data. They're similar to a record player in that there's a "head" that moves over the service, reading the data.
SSDs, or Solid State Drives, are the new kids on the block. They don’t have nay moving parts as they are made from solid state memory, similar to the RAM in your computer.
A disk array is a device that can hold a bunch of HDDs and SSDs, making them accessible over a network, to your servers. Many disk arrays can accommodate bioth HDDs and SSDs. This can be an advantage as HDDs are generally cheaper per TB but SSDs are much faster. There are now intelligent systems that can move data to the fastest storage when it's being used and then back to HDDs when it's under less demand. SAN and NAS
A SAN, or storage area network, is a storage device that is accessed by a server over a network. Although its accessed over a network, a SAN looks to the system that's using it like directly attached storage, like a USB hard drive attached to your PC.
There are several methods that storage arrays can use to be accessed over a network. In general, these are variants of the SCSI protocol that has been around for many years. Two of the more popular storage interfaces are iSCSI that uses the SCSI storage protocol but maps it over the popular TCP/IP network protocol.
Alternately, the Fiber Channel Protocol is also quite popular. It maps SCSI over Fiber Channel. In contrast, a NAS is really just a single purpose computer that can be used for sharing a bunch of storage capacity. When a NAS is first set up the disks it holds need to be configured into a RAID array. If we were looking at a medium level NAS for a small business, it might have a maximum capacity of four drives.
The drives in a NAS are configured to a specific RAOID level (RAID stands for redundant array of inexpensive disks or redundant array of independent disks).
For a NAS with two disks, you'd probably choose between either RAID0 or RAID1. With RAID0, all of the drives are treated as if they are one big drive. So, if you were using a NAS for two 2TB drives, you'd see 4TB of capacity. But if one drive failed, you'd lose all of your data.
If you used RAID1, then all your data would be simultaneously written to both drives. A NAS with two 2TB drives, you'd see 2TB of capacity. But if one drive failed, your data would be safe as it's copied to both drives.
With a larger array of three or more drives you can look at options such as RAID5. In RAID5, your data is written to the disks in such a way that if one drive failed, your data would still be safe. A NAS with four 2TB drives configured as a RAID5 would deliver 6TB of capacity. But if one drive failed, your data would be safe.
A RAID6 array is similar but could survive the loss of two drives.
Checklist: Buying Storage
If we put all that together, you're left with a storage checklist that looks like:
- Current capacity
- Ability to easily add capacity for future needs
- SAN vs NAS
- HDD v SSD vs hybrid of the two
- iSCSI vs Fiber Channel
You should now have a pretty solid understanding of the ins-and-outs of storage. Check in at the same time and place next Wednesday for an overview of laptops.