Does RAID 1 (mirroring) provide any performance improvements?

[Keysplayr]

I was just wondering, I know RAID1 mirrors drives and there will be no write performance gains. But is there any read performance gains? Are HDD requests fed by both drives? Or is one exclusively the production HDD and the other just a clone?

I went RAID1 because I just lost a bit of data when my 2 month old WD 500GB drive took a dump. So I got 2 Hitachi SATA 400GB drives and set them up just for fault tolerance.

Anyway, just curious.

 

[g8wayrebel]

Yes , it will get you as much as 6%(rare and not always even noticeable) increase in speed , but you also split your data between the drives. RAID allows both read AND write to both drives at the same time. The performance increase is generally both ways.
You can chose how much data is split to each write in 3 or 4 increments between the drives for optimized speed for the type you are dealing with.
If you lose one drive you lose all your data since it is divided in very small amounts, max 256k per cycle I believe.

This is a really bad idea if you don't have 10k rpm drives as primary and I would never consider running it w/o backup of all info no matter what if you have any data at all you don't want to lose.
You can gain as much or more speed by optimizing your drivers and eliminating unused processes running in the background , especially if ,when gaming , setting up a gaming profile for it to run only the needed processes.

 

[Keysplayr]

It's RAID1. You're describing RAID0. In RAID1 data is not split between the drives, but an exact clone of each other. Each drive has the same data. The whole purpose of doing RAID1 "IS" to have a backup.

I was just wondering if there were any performance gains with RAID1. I know there is with RAID0, but that's not what I am using.

Thanks

 

[Peter]

There will be a minor to noticeable speed loss in writing, since write data are duplicated to both drives.

On reads, there might be a performance gain if the RAID driver is intelligent enough to distribute read accesses to either drive.

The general expectation should be that RAID-1 performs about the same as a single drive, only with safety against drive failure.

 

[taltamir]

6%? I don't think so...

RAID1 (mirror) you get almost twice the read speed. but slightly lower write speed (by a few percent).

RAID0 (stripe) you get almost twice the read and write speed.

RAID5 is atrocious and is to be avoided... unless you are buying an EXTREMELY expensive controller you are going to be using alot of CPU and bandwidth and have a huge slowdown in everything... and RAID5 is extremely unreliable... with a variety of ways to loose your data.

I had many close calls during my experiment with RAID5... but RAID1 is a charm... if one drive is somehow not found the other has all the data, and it will automatically detect the drive if plugged back in.

 

[corkyg]

Raid 1 provides HDD redundancy but is not truly a backup. Any error, virus, trojan, corruption, etc. on one drive will be on both.

It does provide redudancy to recover from a hgardware failure.

RAID 1 plus a backup of the array to an external drive is well backed up.

Performance in real world applicationsx is not really noticeable by the user.

 

[Keysplayr]

Originally posted by: corkyg
Raid 1 provides HDD redundancy but is not truly a backup. Any error, virus, trojan, corruption, etc. on one drive will be on both.

It does provide redudancy to recover from a hgardware failure.

RAID 1 plus a backup of the array to an external drive is well backed up.

Performance in real world applicationsx is not really noticeable by the user.

Yup. My intention was only to protect myself from hard drive mechanical failure.
As far as viruses and such, I run as much risk as anyone else of contracting one.
Data corruption also is a prob. But I do backup important data to my server once per week.

 

[Fullmetal Chocobo]

Originally posted by: taltamir
6%? I don't think so...

RAID1 (mirror) you get almost twice the read speed. but slightly lower write speed (by a few percent).

RAID0 (stripe) you get almost twice the read and write speed.

RAID5 is atrocious and is to be avoided... unless you are buying an EXTREMELY expensive controller you are going to be using alot of CPU and bandwidth and have a huge slowdown in everything... and RAID5 is extremely unreliable... with a variety of ways to loose your data.

I had many close calls during my experiment with RAID5... but RAID1 is a charm... if one drive is somehow not found the other has all the data, and it will automatically detect the drive if plugged back in.

Are your RAID5 experiences based on using the motherboards onboard controller? Saying that RAID5 is "atrocious and is to be avoided" and "extremely unreliable...with a variety of ways to loose your data" is quite far from the truth if it is setup properly and implement well. And a good controller is not *that* expensive.