Basics of RAID 242
Doggie Fizzle writes "RAID has been common in business environments for ages, and is now becoming more viable and popular for personal computers. This article focuses on the the basics of RAID, and spells things out for beginners or tech veterans. From the article: 'The benefits of RAID over a single drive system far outweigh the extra consideration required during installation. Losing data once due to hard drive failure may be all that is required to convince anyone that RAID is right for them, but why wait until that happens.'"
Current HDD prices... (Score:4, Interesting)
I myself currently have it setup to mirror my data across two 80Gb drives... Four months ago one of the hard disks died (funny buzzing sound, no access) but the manufacturers three year warranty was still valid, so I returned the drive to them for a free replacement. I received the replacement drive and shoved it in, mirrored the data back onto this new second drive and continued as before. If I hadn't have had this setup that data could have been permanently list. It also saves me from writing ten DVDs to store that much.
Still a single point of failure (Score:5, Interesting)
Since a RAID controller doesn't have moving parts, is it less likely than a hard drive to fail?
Windows RAID Over Firewire - Registry Setting (Score:5, Interesting)
The problem, however, is that out of the box Windows refuses to "promote" an external disk to dynamic, which is required on all post-NT4 rigs for RAID.
The solution is to add a semi-documented Registry flag, EnableDynamicConversionFor1394
HOW TO: Convert an IEEE 1394 Disk Drive to a Dynamic Disk Drive in Windows XP [microsoft.com]
Couple that with a cheap 4-bay firewire JBOD box and any spare old enclosures and you are set!
I run 2TB in various RAID configs on my Windows server (main and near-line storage). Have done so since 2002. No problems with the external boxes. The support for external firewire RAID is a little gnarly in Windows 2000 - volume must be mounted as a named virtual directory and cannot be mounted as a letter drive. Later Windows give you both options.
Not until a HDD failed on me... (Score:2, Interesting)
One hdd did fail on that array, and I just replaced it with warranty replacement hdd. No hassle, just carefree usage.
The piece of mind is worth LOT more than those extra drives. I DO NOT like the menial job of building the OS from zero to working state, just because of a hardware failure, WHEN I can just as well avoid it.
Proability of a failure greater than zero (0) is not zero. And I like it to be zero.
Re:Give me RAID 5 (Score:3, Interesting)
There's always software RAID5 too. It would sound like it's slower, but I'm not 100% sure about that (less cpu load for hw raid is pretty much a given though). The other consideration is what happens in a controler failure situation. It might actually be easier to get the software RAID5 to work in a different computer (hw raid will need a new and identical controller to get to the data, which may take a while to get-if it's still available).
raid for desktop - not really worth it (Score:3, Interesting)
As far as desktops are concerned - well, RAID and cheap just don't mix. For instance, if you just want reliability, RAID 1 is enogh (2 drives). If you want reliability + fast writes, you need RAID 1+0, which means 4 drives (RAID 5 only gives faster reads). Furthermore, a good controller is crucial (from my experience, these generally cost upwards of 100$).
Finally, RAID does not subsume in any way a good backup system. I've seen cases where a damaged controller broke both harddrives in a RAID 1. However, for (most) desktop PCs, a good backup system does subsume RAID, since it's generally easy to just use a different computer, and get all the files from the backup.
For me, the excellent piece of software backuppc [sf.net] running on a cheap box (~300$) has worked like a charm. This might not look cheaper than RAID, but considering that I'm using just one box to back up 10 other machines, it's pretty good.
Re:RAID is way overhyped (Score:3, Interesting)
RAID-1 is a simple way to get a "reliable" store.
Note that copying data to RAID [any of them] is *NOT* a backup solution. It's a "temp fix" for storing data.
I use my RAID-1 [two 200GB disks I bought for 130$ each] as a simple "place to dump nightlies" which I then backup to CDR weekly. I do rely on the redundancy of RAID-1 in case I trash my CVS or home dir but my longterm backup strategy includes the weekly CDRs as well.
Some tips for good "short term backuping"
1. Use RAID-1 not RAID-0
2. Use a good file system like reiserFS that's fairly immune to the side effects of being turned off in a hurry [ntfs and ext2 are not]
3. Don't use the raid drive as a home or other frequently accessed directory. Do your backups from a well tested cronjob. The less you play with your raid drive the less likely you are to delete/mess with the files on it.
4. Do backup the files from the raid to a medium like tape or CD/DVD on a regular basis.
5. If one drive should fail, do a backup before you restore the raid. That way if you mess up restoring the raid you don't lose data [particularly beginners do this]
Tom
My non-RAID backup solution.. (Score:4, Interesting)
I use "Smart Synch" software to incrementally copy the desired directories from the working computers to a "Backup server", an older Celeron machine on the network. Separate partitions are set up for each computer that is being backed up. At Midnight the incremental backups are made.
Then at 2:00 a.m., Smart Synch running on the backup server makes another backup to a USB hard drive plugged into it. That USB HD is on a regular plug-in timer so that it only runs during the time of night when a backup to it is being done. The idea there is that the running time is limited and drive life is extended. Weekly, a backup DVD is burned and stored off site. Am I being anal? Maybe.
It can be part of a backup technique... (Score:5, Interesting)
Ultimately, what it comes down to is that mirroring merely makes the hardware more reliable, it is not a backup technique.
It can be part of this nutritious breakfast^W^W backup technique:
0) shut down the box
1) swap a fresh/new/wiped drive for one of the mirrored drives
2) rebuild the RAID
3) store the just-pulled drive appropriately (e.g. off-site) along with a second identical RAID controller
Now if the machine goes completely belly-up (as in a fire) the user can install the secondary RAID controller and the data-laden drive in a fresh machine, add another fresh/new/wiped drive, and rebuild the RAID in the new machine. This may not be terribly convenient nor perfect for everyone but it will be effective.
Remember, kids: just because a particular technique doesn't perform a task all by itself (in this case RAID 1 != backup) that doesn't mean it can't be part of a larger picture.
Re:RAID virgin pops cherry... (Score:3, Interesting)
Re:SCSI RAID Yes, IDE RAID No (Score:1, Interesting)
Also, OSes only understand numeric block ordering, which doesn't always help with understanding which blocks are actually close together (think multiple disk platters). The drive can know where the disk heads and blocks actually are. Also, request queuing means drives can have the next few requests on board, instead of waiting for the next one to be delivered when the current one finishes.
Re:Holy Ads, bat-man! (Score:3, Interesting)
The mystery becomes clearer. Hover your mouse over Doggie Fizzle's name above and see what resources Doggie is affiliated with. Then look at the uri of the "story".
See any connections?
(unfortunately, temojen didn't)
Curiosity question: When did
If it is an organized program, can someone get me the pricing for it?