For this weeks blog I’ve decided to take a break from complaining and concentrate on the theory behind server storage, paying particular attention to Apple’s Mac Mini Server offering.
Mac Mini Server: An Overview
As some of you are aware, Apple has shipped the server edition of its popular Mac Mini line since October 2009, with the main advantages being a second internal Hard Drive and a copy of Mac OS X Server, but at the cost of an optical drive – something rarely used on a server. Due to this Hard Drive configuration a whole new world of storage options is opened to an administrator.
Option 1: JBOD (Just a Bunch Of Disks)
The easiest (and most common – at least with SOHO) setup is to use each hard drive for storage. This could be using the primary Hard Drive for Mail and configuration storage and the secondary Hard Drive used for file storage, or any combination of the above.
Pros: Simple and easy to configure. Very similar to how an end-user might use a second Hard Drive on a workstation.
Cons: No internal backup tool, no redundancy protection from a Hard Drive failure.
Option 2: RAID 0 (Striping)
This is the best use of the built in Hard Drives to maximise speed. This would show the entire storage as one volume of around 1TB and provide around twice the read/write speed when using the built in Hard Drives.
Pros: Around twice the read/write speed as the JDOB setup.
Cons: Double the risk of data loss (lose one Hard Drive and you will lose all the data).
Option 3: RAID 1 (Mirroring)
This is the best use of the built in Hard Drives to maximise redundancy. This would show the entire storage as one volume of around 500GB and provide around the same level of performance but with twice the redundancy.
Pros: Can survive and continue working with one Hard Drive failed.
Cons: Duplication of Data (using both Hard Drives to store the same data, effectively halving your storage paid for), no protection from accidental file deletion and/or corruption.
Option 4: JBOD with Time Machine
This uses the primary drive for all storage for all services and data, with the secondary drive used solely for a Time Machine backup of the main drive. This is the second easiest (and second most popular for SOHO) configuration for administrators.
Pros: Fully internal backups (very difficult to miss a backup!), much quicker restores if required.
Cons: Time Machine cannot completely backup a Mac OS X Server (See Apple Knowledge Base Article “Understanding Time Machine as a Server Backup Tool”.
Option 5: JBOD with OS Segregation
This uses the primary drive for the OS of the server only with all other data (including service data) storage on the secondary drive. The OS data is kept to a minimum (typically 10-15 GB) to facilitate fast backup to the secondary drive.
Pros: Stops any service data filling up the OS drive (and potentially crashing the server), allows selective and quicker restore if required.
Cons: A large portion of the primary Hard Drive storage is wasted.
No option is ideally suited to every situation and every solution. A particular set of requirements may dictate the use of, for example, option 2 for speed, in which case the solution architect would need to take into account the need for complete and often backups.
For a general use server, I tend to lean towards option 5, using a custom shell script to take a disk image (or snapshot) of the boot drive every evening, and a backup to an external Hard Drive daily. Due to the snapshots, the backup will only need to backup the secondary drive. In a real world test, I have been able to restore the boot Hard Drive’s OS is under 40 minutes!
What about you? How have you setup the storage on your Mac Mini? If given the opportunity, how would you? Any points I’ve missed?
Please let us know in the comments below.
P.S. Congratulations on McLaren for the release of their MP4-27 2012 F1 car!
Apple Knowledge Base Article “Understanding Time Machine as a Server Backup Tool”