anyone RAID?
 

I've got a new business venture and will need to do regular backups of the site. I'm thinking of a RAID enclosure, anyone have any suggestions?

Newegg.com - SANS DIGITAL TR8M-B 8 Bay SATA to eSATA (Port Multiplier) JBOD Enclosure

I've been thinking of this one or smaller.

I do have another box that does have a JMB363, and I think a SATA raid controller, not sure,

ASUS P5B LGA 775 Intel P965 Express ATX Intel

This is much better than what you have in mind. 4 x 2.5" SAS SATA HDD Hot-Swap Backplane RAID Cage New. It works perfectly and fits in a large PC case. You can get 1TB 2.5" HDD's for an arm and a leg.

I'm set on 3.5 HDDs because they aren't so expensive for 2TB, I'm even looking at 8 bays because I want have lots of storage. I thought of a cage like that looking at something like the COOLER MASTER STB-3T4-E3-GP 4-in-3 Device Module Hardisk Cage but am afraid it may not fit in my tool free Cooler Master Centurion 5 midtower

I don't know much about RAID setups but I was led to believe the point of running a RAID setup was to avoid having to do back-ups. School me.

oh the convo's I've had. I'll try to put it into something comprehensive and understandable post.

all good redundancy systems do raid and backups (multiple locations). The problem with only raid is if your raid controller dies you still lose everything. Also with backups if the building burns down you still lose everything. Thus any vital data must be backed up multiple times over multiple locations. RAID is primarily to save you the headaches of having to rebuild systems and restore from those backups.

RAID does not provide a back up, because all data is replicated in real time. RAID does provide increased uptime and/or increased throughput by correcting for drive failures.

Backups should ideally occur offsite. A CRON job to a remote FTP server is pretty ideal and saves a lot of labour.

Note that there are a variety of RAID configurations. Cyn is likely talking RAID5.

Standard RAID levels - Wikipedia, the free encyclopedia

I use RAID0 on my home system. Contrary to the Wikipedia article, I see a nearly 2x improvement in drive performance.

RAID5 is used to increase server uptime. A single drive failure will impact performance; but will not cause the server to fail. In most cases, the failed drive can be replaced and recovered hot. RAID5 does not eliminate the need for backups.

StanT could it be you are referring to RAID 1 not 0.

That link is very informative on RAID.

Following is a summary from that link and additions from my experience.

Different RAID levels have different purposes, none of them eliminates the need for (off-site) backup.
With 2 hard drives there are 2 options, mirroring or striping the data.
Mirroring lets the 2 drive act as a single drive with the size of the smaller drive (they should be identical ). Performance is similar to having single drive, gain or loss in performance depends on the setup. In case of single drive failure the drive can be replaced and RAID rebuilt (slowly) without data loss.
Striping lets the 2 drive act as a single drive with the combined sizes of both drives. Performance is close to combined performance of the drives (2x). In case of single drive failure all data is lost (Generally everything is lost, depending on the setup a professional data recovery might get some data back at high cost).

These are general statements, actual performance and redundancy depends on hardware and software included in the setup.

Hope this is of help to someone.
ZB

Nope, I stripe for performance. I run a 2x chance of failure for a 2x improvement in I/O; I do backup everything I care about.

This is the best overview that I've run across for describing all the different RAID versions.

AC&NC - RAID.edu - RAID Tutorial & Benchmarking Tools

And Rekna & Martain are right... RAID just keeps you up during a drive failure. There is still a need for off site backups if you are working on an enterprise level. As was stated... if the building burns down... no RAID or on site backup will save you.

Oh... and for what it's worth... I run RAID 0 on my main PCs to boost performance. They are backed up weekly to my home server which runs RAID 1. I used to run RAID 5... but with Terra byte HDs now being so cheap I fell it is a waste for my home application. The house server also runs a weekly backup to an external HD that I can take with me to friends and family's houses to share larger files than what are conveniently hosted through my FTP site.

Since my parents don't have a home server, I've set their PC up on RAID 5 to give them a boost in speed along with some HD failure insurance (which paid off about a week ago).

One of my friends (who also lacks a home server) felt the need to set up his home PC on RAID 6, although I'm not sure that it has ever paid off for him.

I recently had a RAID-5 setup go south on me. It was the typical failure mode for these things. One drive failed, out of four in the array, I swapped in a new one, and while it was rebuilding one of the other 3 in the array failed.

One failed drive is tolerable, because it can calculate the missing chunks using parity calculations that it sprinkles around on the other drives. But with two drives down, you're S.O.L.

When that second drive failed, I knew I was hosed. Luckily I had backups and wasn't depending on the RAID system, so nothing of value lost, but restoring everything was an unpleasant way to spend a weekend.

Just a cautionary tale. A lot of people set up RAID arrays with several identical (same manufacturer, model, purchased at the same time) drives. If you do that, there is a fairly good risk that more than one of them might decide to conk out at the same time, or close enough to it so that you might be rebuilding during the second failure. In RAID-5, that means badness. In RAID-10 (stripes across mirrors) or 0+1, you have a 1 in 3 (maybe 1 in 2?) shot of losing your data with two drives out, depending on which two go.

Definitely not a replacement for a good backup strategy. Reduces you risk of downtime, for sure, but not a backup system.

And if you do decide to go with RAID, particularly RAID-5, do yourself a favor and buy a mix of drives (same capacity and RPM, obviously), different manufacturers or at least models. It's not like buying tires for your car, where you want them to wear at the same rate; you very much *don't* want that. You want them to all fail at different times, and the only way I know how to do that (aside from retiring them prior to failure after a certain number of hours in service, which is something to strongly consider!) is to go for diversity.