RAID Sucks – Seriously, it does

Old 3 Comments on RAID Sucks – Seriously, it does 568

RAID sucks. Those of you who follow Eli the Computer Guy know that he has said this on many occasions. I fully agree with him, and here are a few reasons why, and a few things you need to think about before recommending it in a solution.

Software RAID vs hardware RAID. Software RAID is not very reliable, and not very fast. It is the cheaper version of RAID, and is often found in lower and even medium end servers and desktops. Most software RAID is not compatible with virtualization technologies.

Hardware RAID isn’t that reliable. The entire point of RAID is to provide redundancy. Well, I should correct myself there. The entire point of RAID in the business environment should be redundancy. Hard drive storage is so cheap these days, it doesn’t make sense to combine two 1 TB hard drives to create a seamless 2 TB. In most cases, you’re using RAID to mirror the information on one drive directly onto another in real-time. The idea being, if a hard drive fails, no problem, the system keeps running on the other drive and when you get a replacement for the failed one, you pop it in and the RAID rebuilds itself and starts mirroring data again. Sounds great, right ? But what happens if the hardware RAID card fails ? Oooops, there aren’t two of those in the computer. You’re out of commission. In the real world, I’ve seen 5 different storage crashes on servers. 4 involved the failure of the hardware RAID card. 1 involved the failure of both hard drives simultaneously.

Recovering data is not simple. Let’s take the scenario listed above; your server’s hardware RAID card dies and for whatever reason the motherboard seems to be having issues as well. You decide that it’s in your client’s best interest to change out the entire server and replace it. Now you need to migrate the data to the new server. No problem, just plug one of the hard drives into an external USB hard drive dock connected to any computer and pull the data off. Simple, right ? Wrong. By using RAID, you’ve been forced to make the hard drives use a unique file system. In most cases, and in any that I’ve seen in the real world, this is an EXT3 or EXT4 file system, which is native to Linux. Plug this into an external USB hard drive dock and you’ll be prompted by Windows saying “you must format this drive before using it”. Great. Sure you could use Linux and mount it up, but in most cases, you’re in a rush because your client’s server is down and they’re dead in the water. You don’t have time to sit there and mount a drive and play with a command-line interface, you need to be dragging and dropping the data onto a new drive with no time to spare. I learned this lesson very recently when a NAS appliance got cooked by a mainline power problem (common where I live).

There are many other downsides to RAID, including the instant duplication of file corruption, and parity inconsistency, which add to the scepticism that RAID is of any real benefit at all in most small to medium sized environments. Truly, if 100% uptime is not an absolute requirement for your client’s operations (and it normally isn’t in non-data center environments), RAID is not something you should consider necessary, and should not be something you rely on for ‘backup’ purposes. Too often we see deployments where RAID has been sold as the sole backup solution. You need to ensure that your clients are taking regular, full incremental backups of their data.

Remember, consider carefully all the pros and cons of any solution before you recommend it or build it into your overall network design.

Author

Martin Lehner

Martin Lehner is an technology professional working for an IT services firm in Whitehorse, Yukon (Canada). He has been working in the technology field for over a decade. With a degree in Business Admin and numerous industry certifications, Martin leads a team of IT professionals that provide third party support for clients. Originally starting a company to offer web development services, Martin quickly realized that clients wanted the entire spectrum of technology services. When Martin is not at work (which is not often, since his company offers 24/7 support), he is busy at home spending time with his family.

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3 Comments

  1. John Abraham October 10, 2014 at 5:12 pm

    Good comments, but on osx software raid drives seem reliable and one drive can be dropped into a new system and booted in case of hardware failure. So I’ve abandoned hardware raid (for the very reasons you mention) and use OSX servers with software raid.

  2. lane March 2, 2015 at 4:19 am

    It really take second to mount a drive in linux

  3. Meeple April 17, 2016 at 1:28 pm

    Software raid sucks yes I agree with this, its more like virtualizing the disk space as if your seeing one disk when in reality the virtualization simply hides the fact of what it is doing. You basically end up with a setup that is invisibly hashing files across all your drives at the same time. That uses up massive amounts of power which most green machines don’t need.

    Hardware based Raid also sucks, it is because manufactures have become greedy. You can only hardware map Raid if you can fork out tons of $$ which is just not worth it. Let’s look at it another way even from a server point of view it makes zero sense. The problem with a Raid setup is if one disk fails all disks in the setup fail at the same time. Something most competent web companies don’t want to manage, where backup servers and disks are a definite priority to protect their customers data. It makes more sense for these companies to invest in disk size vs x amount of disks for Raid.

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