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I Don't Need Backups, I Use Raid1

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Re: I Don't Need Backups, I Use Raid1

#21

Post by its_so_on »

ender7 wrote: post #18

Never underestimate your RAID controller's ability to fail (silently!) and start writing corrupted garbage to your disks.

EDIT: people didn't like my humor. Well, look, the whole thing that you're buying with a raid controller is...redundancy. So if it's not redundant, failing silently, while telling you it's being redundant, how is this different from, say, paying for a house inspection that doesn't get done? If a raid controller is allowed to silently fail, it becomes a post-experience good.

http://en.wikipedia.org/wiki/Experience_good

Meaning that even while you're using it, you have no idea if it works.

My contention is that it's not a raid array if it can silently stop being redundant without telling you.

At best it's an Possibly Redundant Array of Inexpensive Disks.

(The below is how my comment first read.)

(sarcastic) Yeah, it's only prudent to grab a drive out from time to time and make a surprise inspection of whether it's actually filled up a full 4/5th of the way (or whatever) with the actual data the volume is supposed to contain! And the remaining fifth had better look a damn sight like parity information!

Seriously though, a controller that fails like this isn't a RAID controller, since what separates it from a paper plate and a cardboard box. On the paper plate you write "RAID controller" and tape it to an already attached hard drive, and you put the remaining members of the redundant array into the cardboard box. No setup or even connection required!

seriously seriously though, what you're suggesting is unacceptable. that's not a raid controller, that's a scam.

Re: I Don't Need Backups, I Use Raid1

#22

Post by [deleted] »

arethuza wrote: post #3

I once started work somewhere where they did software releases by RAID. Their systems involved shipping a server (effectively an appliance) to the customer with all of the working components on it. However, there was no build or deployment process for these components - so the only way to create a new server was to take an existing one and create a copy. This was done by opening up a working server running with RAID…

[deleted]

Re: I Don't Need Backups, I Use Raid1

#24

Post by ericabiz »

arethuza wrote: post #3

I once started work somewhere where they did software releases by RAID. Their systems involved shipping a server (effectively an appliance) to the customer with all of the working components on it. However, there was no build or deployment process for these components - so the only way to create a new server was to take an existing one and create a copy. This was done by opening up a working server running with RAID…

Same story; different company: http://www.erica.biz/2009/common-mistake-in-business/

It is amazing how even fairly technically-savvy people get sucked into the "RAID=backup" mentality. This story (in the above link) ended up costing the business owner tens of thousands of dollars.

Re: I Don't Need Backups, I Use Raid1

#25

Post by RyanMcGreal »

Fun anecdote: years ago, I worked for a department that had its server on a RAID setup, and when I asked about backups they said, "Don't worry". One day, a drive failed. They replaced it and started restoring from the other drive - which failed mid-sync. The two drives were from the same production lot and died literally within 12 hours of each other.

So: back up your data.

Re: I Don't Need Backups, I Use Raid1

#26

Post by jeromeparadis »

RyanMcGreal wrote: post #25

Fun anecdote: years ago, I worked for a department that had its server on a RAID setup, and when I asked about backups they said, "Don't worry". One day, a drive failed. They replaced it and started restoring from the other drive - which failed mid-sync. The two drives were from the same production lot and died literally within 12 hours of each other. So: back up your data.

It happened to me. It happens the drives had a bug where there death time was hardcoded in the drives. Past a predetermined time of usage, they would fail. Of course, I never believed RAID was a backup strategy so I was able to recover.

Re: I Don't Need Backups, I Use Raid1

#28

Post by eli »

its_so_on wrote: post #21
ender7 wrote: post #18

Never underestimate your RAID controller's ability to fail (silently!) and start writing corrupted garbage to your disks.

EDIT: people didn't like my humor. Well, look, the whole thing that you're buying with a raid controller is...redundancy. So if it's not redundant, failing silently, while telling you it's being redundant, how is this different from, say, paying for a house inspection that doesn't get done? If a raid controller is allowed to silently fail, it becomes a post-experience good. http://en.wikipedia.org/wiki/Experience_goo…

Of course a RAID controller isn't supposed to fail silently, but it can and it does. I can't think of many complex pieces of technology that work 100% all of the time.

Re: I Don't Need Backups, I Use Raid1

#29

Post by furyg3 »

Dud, Flood, & Bud.

Duds are hardware that goes bad, like a disk drive, network adapter, NAS, or server. There are an infinite number of ways and combinations things can break in a moderate sized IT shop. How much money / effort are you willing to spend to make sure your weekend isn't ruined by a failed drive?

Floods are catastrophic events, not limited to acts of God. Your datacenter goes bankrupt and drops offline, not letting you access your servers. Fire sprinklers go off in your server room. Do you have a recent copy of your data somewhere else?

Bud is an accident-prone user. He accidentally deleted some files... the accounting files... three weeks ago. Or he downloaded a virus which has slowly been corrupting files on the fileserver. Or Bud's a sysadmin who ran a script meant for the dev server on the production database. How can we get that data back in place quickly before the yelling and firing begins?

There are more possible scenarios (hackers, thieves, auditors, the FBI), but if you're thinking about Dud, Flood, & Bud, you're in better shape than most people are.

Re: I Don't Need Backups, I Use Raid1

#30

Post by its_so_on »

eli wrote: post #28
its_so_on wrote: post #21

Earlier quoted context omitted.

EDIT: people didn't like my humor. Well, look, the whole thing that you're buying with a raid controller is...redundancy. So if it's not redundant, failing silently, while telling you it's being redundant, how is this different from, say, paying for a house inspection that doesn't get done? If a raid controller is allowed to silently fail, it becomes a post-experience good. http://en.wikipedia.org/wiki/Experience_goo…

Of course a RAID controller isn't supposed to fail silently, but it can and it does. I can't think of many complex pieces of technology that work 100% all of the time.

You don't think that something that only exists to create disk redundancy is in a different category from complex pieces of technology that don't have this in their name?

I simply disagree that you should "never underestimate" your raid controller's ability to fail silently (which is the comment I was replying to). If this is even on your radar you don't have a RAID controller.

This is literally like saying. "Never underestimate your digest algorithm's ability to hash the same file to different values, making the checksum seem to fail." That's not a digest algorithm, that's a randomized print statement.

A RAID controller you should 'never underestimate' the ability of to fail silently is literally sometimes the same as a paper plate with "raid controller" written on it. Call it "sometimes raid". or "maybe raid" or "more raid". You don't have a raid controller.

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