Windows' Raid 5

Page 2 - Seeking answers? Join the AnandTech community: where nearly half-a-million members share solutions and discuss the latest tech.

Nothinman

Elite Member
Sep 14, 2001
30,672
0
0
Raid 0 is about having two exactly identical partitions. When writing data, the data must be written to both drives; but when reading data, most, if not all, hardware raid cards will read half the data from one drive and half the data from the other drive.

That's RAID1.
 

drag

Elite Member
Jul 4, 2002
8,708
0
0
My question is if Windows XP's software RAID 0 is smart enough to read half the data from one drive and half the data from the other drive.

Windows will use algorythms to try to figure out automaticly the quickest way to read the data off of the harddrive. They would be tested and the engineers will try to balance out the differences in such a way to make it as quick as possible for general computing stuff, or whatever they felt would be ideal for the type of setups people would want to use RAID for.

Truth is though that in 'clinical' style benchmarks with various different benchmarking suites show that on the scale that we are dealing with that irregardless of what RAID type your using the advantages in performance over a single drive is not that great. Especially with RAID 0/1 setups.

It's just due to the nature of how drives work and how file systems work.

At this point its more for a extra layer of data protection and a bit for higher aviability.

The most cost effect approach for a regular desktop use is to get the biggest and fastest drive you can reasonably afford and do backups of important information onto DVDs.
 

Brazen

Diamond Member
Jul 14, 2000
4,259
0
0
Originally posted by: Nothinman
Raid 0 is about having two exactly identical partitions. When writing data, the data must be written to both drives; but when reading data, most, if not all, hardware raid cards will read half the data from one drive and half the data from the other drive.

That's RAID1.

Dang it, that's what I meant.
 

Brazen

Diamond Member
Jul 14, 2000
4,259
0
0
Well, I popped in a second, exactly identical, harddrive, but the "add mirror..." option is greyed out when I right-click on the system partition. :eek:
 

imported_goku

Diamond Member
Mar 28, 2004
7,613
3
0
Originally posted by: nweaver
did you read the thread? It's mentioned several times that raid is for uptime/redundancy in H/W, no one here claims it's for a backup, as most of us realize that it's a rediculous prospect.

then again, could one technically use as a backup storage (meaning your main data is on Computer A and the backed up data is on File server which is in Raid 5) correct?
 

Sunner

Elite Member
Oct 9, 1999
11,641
0
76
Originally posted by: randalee
Originally posted by: Nothinman
We have hundreds of servers and I've never seen a dying drive affect the rest of the array.

Same experience here. We use both HP and Dell servers, and I've never had that type of problem. And we're talking hundreds I work with as well.

I'll third this, have had plenty of drives go bad in our HP servers, in RAID1's, 5's, and 10's, and never had a problem, just replace and rebuild.
 

Smilin

Diamond Member
Mar 4, 2002
7,357
0
0
I used to work in a group that took calls from admins like yourselves with failing drives. I've seen it plenty of times. If you have a hundred or more servers you'll see it eventually. It will usually manifest itself as a nasty reboot followed by a "missing or corrupt c:\windows\system32\config\system.ced" or something. You'll find the remaining drives in the array are fine but the data has corruption.

Those of you that know me know I'm not pulling this out of my ass :)
 

Sunner

Elite Member
Oct 9, 1999
11,641
0
76
Originally posted by: Smilin
I used to work in a group that took calls from admins like yourselves with failing drives. I've seen it plenty of times. If you have a hundred or more servers you'll see it eventually. It will usually manifest itself as a nasty reboot followed by a "missing or corrupt c:\windows\system32\config\system.ced" or something. You'll find the remaining drives in the array are fine but the data has corruption.

Those of you that know me know I'm not pulling this out of my ass :)

I trust you not to pull stuff out of yer arse, so don't worry about that ;)

All I'm saying is, I don't believe that to be a universal problem with hardware RAID controllers.
Oh and the day one of our servers spit out errors about C: and stuff, this is gonna be one surprised admin considering they're running Linux or Solaris ;)
 

gsellis

Diamond Member
Dec 4, 2003
6,061
0
0
Originally posted by: goku
Because I would have otherwise created a new thread...
Why? Are you expecting a different answer? Yes, you can recover R5 software volumes and I do believe you can backup the volume information to recover them (have not played with it since NT 4 SP1). That has been explored.

Software RAID is as reliable as you make it. If you are lack at administration, it is not reliable. If your administrative policies are lack, so is your reliability. If you put R5 software on a Hardware R5 volume, you can create the world's slowest R5 set (sorry, had to add it as we had someone do this once with hillarious results.)

But there are arguments both ways on reliability. Although you can hot-swap, a planned outage to replace a damaged drive is a better policy from what I remember (I am the desktop OS guy... ;) )
 

Jadow

Diamond Member
Feb 12, 2003
5,962
2
0
I just installed a server with an HP Smart Array 641 with 4X 140gb 10krm SCSI Ultra 320 HD's on RAID 5, and it is freakin sweet.

Working with Servers is so fun.
 

jtusa

Diamond Member
Aug 28, 2004
4,188
0
71
On Windows 2K3 Server, if you have to reinstall the OS you CAN recover the array. I've done it before.

ETA: Just to clarify, that includes formatting the system drive (completely wiping the OS), and being able to recover after a fresh install.