Server Hard Drives

Choosing server hard drives

Drive type

There are three main types of server hard drives: hard disk drives (HDDs), solid state drives (SSDs), and hybrid drives. HDDs use spinning disks to store data, read and write data much slower than SSD and are generally cheaper. SSDs store data on interconnected flash-memory chips, read and write data much faster than HDD and are typically more expensive than HDD but cheaper than hybrid drives. Hybrid drives have both spinning disks and flash memory chips, read and write data faster than HDD but not as fast as SSD and are usually the most expensive option. Your choice of drive type will be governed by the capacity you need as well as your available budget. High capacity SSDs are prohibitively expensive so despite their performance advantages, HDDs will be the logical choice for most organisations needing to store and access a lot of data.

Capacity

Disk capacities are continuously evolving as technology advances and there’s a wide range of drive capacities available from 146Gb up to 20Tb and above. SFF are available in a wider range of capacities than LFF drives but if you’re looking for the highest possible storage capacities, LFF drives provide a cheaper cost per GB and larger storage capacities. When assessing how much capacity you need, ensure you plan for the future as file sizes continue to increase exponentially so you’ll want plenty of space or room to add more storage as your data grows.

Interface

Both HDDs and SSDs are available with a variety of interfaces that correspond to the type of communication system (or bus) that a given computer uses. The different types have evolved over time so you’ll need to look in the manual or inside your device to understand which type is supported to ensure you’re choosing the correct drive. The common interfaces you will typically find in server drives include SAS, SATA, M.2, U.2, fibre channel and PCIe with legacy connections such as IDE/PATA and SCSI found in older server models.

Size

Server drives are available in different physical sizes including 2.5” (SFF), 3.5” (LFF) and M.2 so check the size and quantity of vacant drive bays your server has available before buying. Ideally, your server operating system should be installed on different drives to your applications and data. If there are M.2 slots available, a couple of SSDs are ideal for the OS to give you fast boot up and access with redundancy and failover. Most server chassis are designed to house either 2.5” or 3.5” drives although some can house both. You can fit more 2.5” disks in a server but if you need higher capacity storage, 3.5” disks are available in higher capacities.

Speed

The speed at which a server hard drive accesses data depends on several factors including the drive type, interface type, transfer rate (the data read/write speed) and, for hard disk drives, the rotational speed of the platters. As mentioned above, SSDs are faster and offer superior performance than HDDs. An SSD can deliver a read/write that’s almost 5x faster than that of an HDD. An NVME drive is faster still with an effective write speed over 10x that of a hard disk drive.

Hot-swappable drives

Most of the latest servers use hot swappable (sometimes called hot plug) drives. Such drives can be removed and replaced whilst the server is running without the need to first shut down the server. This type of hard drive is useful for servers because it allows for easy replacement of faulty drives with no loss of business continuity. Refer to the server specs to check whether the server supports hot swap drives or not.