Why using a Drobo for Apple’s Time Machine might not be a good idea

Update 12/27/10 It is possible to partition your Drobo, so that you have a segmented amount of storage space for Time Machine to run in. In the case listed below, the client used the Drobo as a Time Machine drive, so over time the volume filled up with more and more data, and the client expanded the Drobo at least once in order to keep up with the growing Time Machine retrospective back up. It is possible and recommended that if you want to use a Drobo for TIme Machine you set it up with a partition just for TIme to run on. See this link from Drobo’s support page with more info on how to do this. It is important to note that, if you re-partition your Drobo, you will need to back up your data as re-partitioning your Drobo WILL ERASE all of the data stored there.

We’re fans of the Drobo data storage device here at MacMedics. They are a fantastic, low-cost solution for storing large amounts of data with relative safety.

In a repair that I’m working on that involved a Drobo 4 bay device, I’ve come up with some thoughts on why a Drobo device is not a good idea for use as a Time Machine volume.

1. We already know that Time Machine really puts a strain on the directory of a hard drive. We commonly see TIme Machine volumes with severely corrupted directories. When you combine the action of Time Machine along with the process that Drobo uses to protect and preserve your data, I think that intensifies the strain on the directory of the RAID.

2. Time Machine is a workout for any hard drive when it’s running all the time, and we have seen a few hard drives that have succumbed to the strain of that duty. In the case of the Drobo combined with Time Machine, the drives just go non stop all the time at a fairly intense level. When you consider that all that hard drive activity could prematurely shorten the life of a hard drive in your Drobo. Don’t forget that increased hard drive activity means more heat which can shorten the life of a hard drive.

When you consider both of these factors and add in the fact that having an ever expanding Time Machine volume, Drobo is not the best choice as a Time Machine volume.

Time Machine is the most powerful feature of Leopard and Snow Leopard. Having said that, having a Time Machine backup is highly recommended, but in almost all cases we DO recommend a “Double Backup”. In most cases this can be accomplished with one hard drive. If you have a large hard drive, you can create a partition that’s slightly larger than your hard drive, and then use the remaining amount of space for Time Machine. The trick here, is to clone you hard drive to the small partition and allow Time Machine to use the large one. This way if you ever have a failure, you can boot off your “clone” and then have access to you Time Machine data from as recently as one hour ago.

See my post about Time Machine and for a link to a program that will allow you to adjust it’s frequency here.

See my post about doubling your Time Machine back up here.

If you have a LaCie external hard drive, especially the LaCie Big Disk from a few years ago, MacMedics strongly recommends replacing it. Several years ago when the largest inexpensive hard drive was in the 250 to 500 GB range, this type of “striped” hard drive RAIDs (also called RAID 0) were super popular. It allowed you to have a reasonably inexpensive LARGE single hard drive (made of of two smaller cheap hard drives). This design was driven by the effort to give users a low price on a large amount of space. Having a hard drive volume made up of two drives striped together is risky because it’s essentially a RAID system designed for performance not protection. You are doubling your chances for a major problem because you have two drives (working in tandem) instead of one. If one drive fails you lose the data on the RAID meaning that you lose all of your data (it would be far less risky to have TWO separate hard drives, that way if one failed you would still have the data on the other one). You are also in situation where two drives create twice the heat, thus increasing the drive temperature and decreasing the life span of your two hard drives in a single case.

Many computer users (both Macintosh and PC) don’t even know that they are using a RAID 0 hard drive system with TWO hard drives inside. RAID 0 is designed for speed and performance, not redundancy or protection. If you use a RAID 0 drive, you must ensure you have it backed up, because if a drive dies or the RAID controller fails or the RAID gets damaged by a corrupt directory or something, it’s bad news for your data. Read more about the different types of RAID systems here.

Data loss from these types of “two drive” systems are becoming more and more common, as these “Big Disks” start to fail from age. If you have a RAID system like this, you need to make sure you have a tested and automatic back up (using two striped or spanned RAIDs to back up one to the other is okay), to ensure your data is protected. Storing your data on a “performance” RAID is a VERY bad idea, and it’s equally bad to use such a drive as back up system. If you do lose your data on a “spanned” or “striped” RAID the data recovery costs are far more then if you were just working with a single non-RAID hard drive. Also, don’t forget that if your system is more than three years old, you should consider “retiring” it anyways, see our website at http://www.HardDrivesDie.com for more info on that.

This type of device (as pictured above) has no internal fan, so this device has history of “over-heating”. Hot hard drives fail faster, so using TWO hard dives inside one enclosure with no fan is just asking for trouble.

Hard drive prices are at an all-time low, so this is a great time to replace an order drive with a new, faster, more robust hard drive.

Update 10/1/10 - If you have one of these drives, it really should be retired. Not ready to chuck it in the trash just yet? Here’s a great idea for “retiring” a 2-Drive “spanned” RAID like the type mentioned above. Use the drive as an off-site back up! Buy a new larger drive, copy all of the data over, and then turn off the old drive, and take it off-site. This completes TWO segments of the “Holy Trinity” of data protection. 1. Redundancy AND 2. Off-Site Back Up. You only need an automatic back up system to achieve all three segments. Yeah, it’s an old drive, but it’s not going to age much sitting on a shelf (powered off) at your parent’s house.

Another great idea that you can use in conjunction with the idea above, is to buy a Drobo. A Drobo RAID device will allow you to copy all of your data to it, and you get some good data redundancy built in, as a Drobo is a “protection” RAID. If one drive fails, you still have all you data. Need a Drobo? We always have them in stock and most of us at MacMedics have one at home.

See this Blog post from a MacMedics client who had one of these LaCie “spanned” RAIDs and lost his data.