Is raid necessary for a modest server?

This is a bit of a subjective question, but I want to run it by everyone here:

I've been thinking of building a basic linux server that would consist of one or more internal hard drives and then multiple external USB/eSATA drives on a rotating offsite backup schedule.

When I think server storage, the first thing I think is going with a RAID solution. But these days, I'm looking around at the storage sizes of individual disks and I'm questioning if RAID is even really necessary anymore.

To me, different raid configurations can give the following advantages:

• Drives raided together to appear as one huge volume
• Striped drives for increased read/write speed
• Data Redundancy

And now, the reasons I feel like raid isn't really necessary for me

• I can get individual 1.5+ TB drives, which is big enough for me for now
• I don't need amazing read/write speed on a server that is not accessed constantly by many people
• I have enough rotating data backup solutions for my server that the raid data redundancy doesn't seem necessary

I just want to run this by the SF crowd to make sure I'm not missing something obvious. It just doesn't seem like its necessary for a basic server and if anything it seems like it would be just another thing to deal with. Any opinions?

From serverfault Jakobud

• With drive sizes where they are, RAID1 is a no-brainer to my way of thinking. The reason I RAID at home is to prevent data-loss events, not for better performance. And I'm not working with data sizes large enough to justify parity RAID setups in order to keep the cost of redundancy down.

  From sysadmin1138

• Well RAID isn't a backup so having it won't negate that need. RAID is primarily to provide better availability of your data as well as improve performance. In a home setting neither of these are critical in my opinion so as long as you are comfortable with your backup I would say that your thought process seems good to me.

  One quick note though. With LVM you don't need to use RAID to have a volume that can span multiple drives.

  From 3dinfluence

• Backup and fault-tolerance aren't the same thing. RAID isn't backup. RAID is a fault-tolerance mechanism (primarily) to improve availability. Backup isn't a fault-tolerance mechanism.

  Would you want to restore the server from backup in the event of a disk fault? I wouldn't. RAID-1 is cheap, cheap, cheap insurance, to my mind.

  In a small business context (which is more appopriate for Server Fault discussion), the cost associated with downtime will quickly dwarf the cost of a second hard disk drive. For your home situation, that might not be true.

  If you value your time, though, I'd go ahead and do RAID-1 on your home server. Otherwise, you'll be restoring and rebuilding when you have a disk fault. Given how cheap disks are, I'd go with the second disk.

  As I'm fond of telling people: Disks are mechanical. It's not a question of "if" they fail, but rather "when". Hopefully that "when" happens after the disk's production-use lifetime, but it might not be.

  From Evan Anderson

• Talk to your users. Is your wife OK with having the reduced availability in the case of a failure? Keep in mind that 'reduced availability' is both the server AND your time to recover it. Also keep in mind that any failure WILL happen at the worst possible time.

  Let's say that your server is the backend for your MythTV setup. Let's also say that your wife has come to rely on it (because it's been good to her so far.) How much cred will you lose long will you be in the doghouse when DWTS doesn't get recorded because the server failed? (Or worse, your wife is looking for a new job and she used her 'home' email address on that server that just failed.)

  On the other hand, if this is your own personal tinkering machine and you have no girlfriend or wife, then it doesn't matter so much and you can be as much of a cheapskate as you'd like. :)

  -Dave

  From toppledwagon