I still don't see a significant advantage to using RAID

Datalyss · 01-06-2009, 04:06 PM

Even after reading the articles @ both The Tech FAQ and Wiki, I still don't get it. I mean if your buying hard drives, why not just use them as separate drives? Seems to me there may be more problems than advantages in combining two or more drives.

oldskool · 01-06-2009, 10:03 PM

Quote:

Originally Posted by Datalyss

Even after reading the articles @ both The Tech FAQ and Wiki, I still don't get it. I mean if your buying hard drives, why not just use them as separate drives? Seems to me there may be more problems than advantages in combining two or more drives.

Well I am not by any means an expert on this, but the idea for (some) types RAID is for keeping data safe from system crashes. It is called "fault tolerance".

RAID 0 has no fault tolerance.

RAID 1 is mirroring. That is ok, except when copying data, it puts a load on the CPU more than other types of RAID.

RAID 5 is common, it is fault tolerant AND there is parity checking as well.

With RAID 5, if one drive crashes you still have all your data intact. You need 3 drives minimum for RAID 5.

Poizen22 · 01-06-2009, 10:29 PM

i thought raid 0 oferred performence boost speed wise???

oldskool · 01-06-2009, 11:06 PM

No fault tolerance. One drive crashes, the shooting match is over. Both drives need to stay up. Speed isn't everything.

Datalyss · 01-06-2009, 11:48 PM

Quote:

Originally Posted by Poizen22

i thought raid 0 oferred performence boost speed wise???

Quote:

"Striped set without parity" or "Striping". Provides improved performance and additional storage but no fault tolerance. Any disk failure destroys the array, which becomes more likely with more disks in the array. A single disk failure destroys the entire array because when data is written to a RAID 0 drive, the data is broken into fragments. The number of fragments is dictated by the number of disks in the array. The fragments are written to their respective disks simultaneously on the same sector. This allows smaller sections of the entire chunk of data to be read off the drive in parallel, giving this type of arrangement huge bandwidth. RAID 0 does not implement error checking so any error is unrecoverable. More disks in the array means higher bandwidth, but greater risk of data loss.

Source: RAID - Wikipedia, the free encyclopedia

Saxon · 01-07-2009, 12:07 AM

If you ask me RAID if fundamentally flawed, and further implementation should be discouraged. In all honesty why? Raid 5 I can understand but unless a machine is in use 24/7/365 simple back up software can do it, When i run my own company I got a panicked call from some guy who litterly knocked the server over and one of the hard drives was clicking he would have lost a **** load of company data because the last support company made them use RAID 0. If it wasnt for me installing a Tape drive a week before there would have been a fair bit of data lost.

In my mind this is how any one should run there back ups an data storage:

2 Identical disks, 1 tape drive and Backup Exec. Nightly there is a tape back up of all critical files to the tape that is taken off site at 9pm there is a 2nd back up of the primary drive to the 2nd hard disk.

If one drive dies there is the 2nd copy on a drive that can be ghosted to a replacement, if somthing happend to the machine there is the crittical back ups on the tape.
I also recomended a critical back up off sight of all the drives once a month a day or so before pay day, it's not the most ideal soloution but I have never seen this meathod fail as at any one time there is atleast 3 copys of the critical data 2 copys of all the data on site and 1 other copy of site no more than 28 days old.

carnageX · 01-07-2009, 12:21 AM

Can't remember where or who said it...but this topic reminds me of it:

"What is RAID0? Well the 0 means how many files you're gonna get back if something goes wrong."

Hefemeister · 01-07-2009, 02:14 AM

Well for starters a raid 1 or 5 or 10 should never be looked at as a backup solution. No matter what you run you need backups.

Some of the importance of raid has been lost with increasing drive size. Back in the day I built raid arrays with 7 or 8 36gb scsi drives just because you could not realistically get drives large enough to hold a huge company database.

What companies need raid arrays for is the fault tolerance. Even though you have backups if a hard drive fails you cannot tell 100+ employees that they cannot work because a hard drive failed. If a hard drive goes down the system keeps running. Then the IT department can come in a night. They can drop the array, put in a new drive and rebuilt it. The next day none of the employees have any idea that there was a problem. Trust me I have spent my share of nights rebuilding arrays after a drive failure.

Raid0 is a bit faster but it is just for fun. I run a couple of raptors in raid0 and sure it is faster. I only install my os and apps on it and keep no important data. I just do it to say that I do. The speed increase does not outweigh the risks for a critical system.

zedman3d · 01-07-2009, 03:31 AM

Not to mention performance nuts RAID their primary OS drives.

meat_helmet · 01-07-2009, 08:03 AM

Yeh raid is only good for raid 1. I used to use 2 old 80GB seagates in raid 1, and they were noticably faster than my current 500GB 7200.11 seagate.

Still, this should only be used for OS and apps as already said. Data should be on another disk and backed up.

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