Proof That RAID Is Not Intended For Backups
 

I found this rather humorous since I usually preach to other members here on this site that setting up RAID is not setting up backups.

http://journalspace.com/this_is_the_...a_whimper.html

From the page:

"Tuesday:

Journalspace is no more.

DriveSavers called today to inform me that the data was unrecoverable.

Here is what happened: the server which held the journalspace data had two large drives in a RAID configuration. As data is written (such as saving an item to the database), it's automatically copied to both drives, as a backup mechanism.

The value of such a setup is that if one drive fails, the server keeps running, using the remaining drive. Since the remaining drive has a copy of the data on the other drive, the data is intact. The administrator simply replaces the drive that's gone bad, and the server is back to operating with two redundant drives.

But that's not what happened here. There was no hardware failure. Both drives are operating fine; DriveSavers had no problem in making images of the drives. The data was simply gone. Overwritten.

The data server had only one purpose: maintaining the journalspace database. There were no other web sites or processes running on the server, and it would be impossible for a software bug in journalspace to overwrite the drives, sector by sector.

The list of potential causes for this disaster is a short one. It includes a catastrophic failure by the operating system (OS X Server, in case you're interested), or a deliberate effort. A disgruntled member of the Lagomorphics team sabotaged some key servers several months ago after he was caught stealing from the company; as awful as the thought is, we can't rule out the possibility of additional sabotage.

But, clearly, we failed to take the steps to prevent this from happening. And for that we are very sorry.

So, after nearly six years, journalspace is no more.

If you haven't yet, visit Dorrie's Fun Forum; it's operated by a long-time journalspace member. If you're continuing your blog elsewhere, you can post the URL there so people can keep up with you.

We're considering releasing the journalspace source code to the open source community. We may also sell the journalspace domain and trademarks. Follow us on twitter at twitter.com/jsupgrades for news."

Pretty sad really. Perhaps proof positive that one should never put all ones eggs in one basket...

So they relied completely on hard drives, no tape backup whatsoever? Then thats their own damn fault. I also learned the hard way about not relying on hard drives alone for backups. I worked for a small company two years ago, and even they had tape backups running.

I never used RAID, but even I realized that due to it's applications, RAID is obviously a poor choice for backups. It is mainly intended for faster data transfers, great especially for video editing, etc; but the obvious drawback is stability, plus a hell of a lot more wear and tear on the drive to say the least.

Backups on optical and tape media for redundancy is the way to go.

Actually the real reason behind RAID is for drive failures to keep data integrity in order to replace a failed drive without it impacting the system, filesystem, etc. Drive goes down, doesn't take complete system down with it. System stays running til failed drive can be replaced, that's the reason for RAID.

Setting up RAID to for faster data transfers is not usually the goal, that's just a rule of thumb per se with any hard drive setup. Everyone wants faster data transfers, RAID or no RAID setup, that's just a given.

There is nothing wrong with using hard drives for backup, it's cheap and reliable. The problem was not the choice of backup medium, but the lack of any backup mechanism.

Both RAID, and backup have their individual uses. Running hard drives in mirror configuration has saved me a lot of work and inconvenience in the past. While I've never had to do a full 'real' recovery from a backup, I've had to restore odd files I deleted wrongly thinking I no longer needed them.

Jeebiz, I would be interested in your reasoning behind your obvious drawbacks, specifically the one about stability.

On a similar note to the above - with larger drives, even RAID 5 may begin to fail to recover data in the event of a disk failure. See Here.

Basically, it turns out that as drives get above 2TB, the rate of unrecoverable read errors is reached in a RAID 5 array. In the event of a disk failure, your are almost guaranteed to have a unrecoverable read error.

Makes for interesting reading...

--Ian

This neatly displays the difference between "redundancy" (useful to keep you going when something goes wrong), and "backup" (a spare copy kept someplace else).