Today I'm going to talk about hard drive enclosures. These are devices that have no processing units in their own right, only the equipment to power hard drives and provide communications to them from external controller cards. Dell and HP both make them, and they're available in both SCSI and SATA/SAS flavors.


The HP enclosures are the MSA20 and the MSA30. The MSA30 is the SCSI version. It can hold up to 14 hard drives that are 3.5” in size. These are hot swap units, so if supported by your operating system and controller you can replace or add drives without shutting down.


The MSA20 is similar, but it accepts 3.5” SATA or SAS hard drives. It's a hot swap system also and can hold up to 12 drives.


Dell has the PowerVault 220s, the MD1000, and the MD1120. The PV220s is their equivalent of the MSA30. It's a hot swap enclosure that can take up to 14 SCSI hard drives, 3.5” in size. The MD1000 is the SATA/SAS version, and it will take up to 15 hard drives, again in the 3.5” size.


The above systems are all 3U in size, but if you're hurting for space in a rack, you could look at Dell's MD1120. This machine takes 24 SAS/SATA drives that a 2.5” in size. The smaller drives mean the system is smaller, only taking up 2U in space. Also, it gives you greater granularity in how you manage your hard drives. Drives that are physical larger are sometimes easier to deal with, so this isn't a solution for everyone.


There are ways to connect these machines in groups or chains, so you can extend the amount of storage available. The limits depend on the devices themselves and also on the controllers and servers that are connected to them. The product manuals explain the differences, and we're happy to answer questions as best we can, ourselves.