Does RAID 1 have a speed penalty?

[Navid]

I have my data on my first hard drive.
I make automatic schedules backups of my irreplaceable data onto my second hard drive.
This provides redundancy. So, if either of the two drives dies, I can still get my data.

But, if my second hard drive dies, I will lose all my backup history. I will be left with my current data. If I want to get to my data the way it was 2 months ago, I will not be able to.

I am thinking of getting a third hard drive and setting up a RAID 1 to use as my second hard drive. So, my second hard drive will be mirrored.
I think that would solve my problem.

One question:
If the second hard drive is RAID 1, will it be slower than if it was just a single drive?
I believe that RAID 1 improves read speed. But, does it make an impact on write speed?

I have no experience with RAID. So, please explain in detail. Thanks!

 

[Nothinman]

Assuming that you're running Windows and will be using the onboard fakeraid then it depends on how poorly written the driver is for that fakeraid chipset. In general writes may be a bit slower because there's two of them and they're on the same PCI bus but reads could either be the same or faster if the driver is smart enough to split them between the two drives.

And also remember that if you're using the onboard fakeraid for your motherboard then your mirror is tied to at least that chipset and possibly that model board.

 

[dclive]

...which is a really, really bad idea. If you MUST use RAID, use Windows RAID or buy a card; at least with either of those it will work if you move to another computer.... To me a much better idea is buying Acronis Disk Image and making a disk image every X number of days, with incrementals along the way. Much better use of resources, too, since you can use the disk for other things too.

 

[Nothinman]

Windows software RAID is usually not an option since AFAIK no client version of Windows supports RAID1 or any level of redundant RAID.

 

[Navid]

Originally posted by: Nothinman
And also remember that if you're using the onboard fakeraid for your motherboard then your mirror is tied to at least that chipset and possibly that model board.

Are you saying if I want to move to a different motherboard, I will have trouble to transfer the drive?
Would it be difficult or impossible?
Or, are you talking about a different problem altogether?

 

[dclive]

That's exactly what we're saying. Using motherboard-integrated RAID is a bad idea.

 

[johnos]

I got a "server" sitting next to me with RAID1 on it. Its a decent computer and gets low usage as it just sits in the corner being a server. There isnt a huge speed penalty on writes, nothing serious, reads are similar, possibly a bit of a hit. The thing that i first noticed when i got the computer was the noise, 2 HDDS writing and reading in sync makes a hell of a lot of noise...

And as a backup system we have an external HDD and Acronis True Image. It makes a full backup weekly every monday, and backs up all the critical data daily.
It works well, but then again, files are rarely deleted unless for some specific reason or by accident, and if it is accidental we just get them from the backup, so we have no real need for backup history, chances are that all 3 hardrives won't fail within the one week and we will still have all the data we need.

If you do want backup history i have an idea that is borrowed from a friend, it also protects you a bit mroe against things like theft and fire.
use 2 external Harddrives as backup drives, swapping them weekly. keep the unused drive at work, or in the garage, or at your parents house, etc etc. As long as its not with all your other computer stuff. That way if your house burns down (hoping the garage doesnt go to, thats why offsite is better) or someone steals your computer and external HDD you only miss out on a maximum of a weeks work or whatever, you also keep all your backup history. depending on how much stuff you have got too backup as well its reasonably cheap and its quite effective.

Also, can someone explain why onboard RAID is bad, like surely if my motherboard failed I would still be able to go and plug a RAIDed HDD into any other SATA port on another computer and still have everything there? It would just be that I would have to rebuild the array correct?

 

[dclive]

The data format is proprietary - that's the entire problem. So if you can't find the same RAID controller...

 

[Nothinman]

Well the RAID information is proprietary, the data on the drive is still in whatever format you stored it in. And with a mirror it probably wouldn't be too much extra work to recover the data but you wouldn't be able to just plug both drives in and have the array come up.

 

[Navid]

Originally posted by: Nothinman
Well the RAID information is proprietary, the data on the drive is still in whatever format you stored it in. And with a mirror it probably wouldn't be too much extra work to recover the data but you wouldn't be able to just plug both drives in and have the array come up.

If I plug only one of the two drives to a motherboard and set it up as a simple drive (not RAID), will I not be able to access all the data?

 

[Nothinman]

If I plug only one of the two drives to a motherboard and set it up as a simple drive (not RAID), will I not be able to access all the data?

I'm not sure, I know I don't trust those onboard fakeraid chips enough to test it though.

 

[dclive]

If it isn't RAID'd, there won't be a proprietary RAID container made, so there shouldn't be an issue. It's only when you make a RAID container and put drives into it that it becomes proprietary.

 

[Nothinman]

Oh yea, I misread that first time. Setting it up as a single drive would be fine.

 

[Navid]

Can I set up RAID 1 for a part of a drive?
I mean can I only mirror a part of the drive?

Let's say I have a 300GB drive and a 500GB drive. Can I set 300GB of the 500GB drive to be RAID 1 with my 300GB drive and still use the remaining part of the 500GB drive as a regular partition?

 

[postmortemIA]

Originally posted by: Navid
Can I set up RAID 1 for a part of a drive?
I mean can I only mirror a part of the drive?

Let's say I have a 300GB drive and a 500GB drive. Can I set 300GB of the 500GB drive to be RAID 1 with my 300GB drive and still use the remaining part of the 500GB drive as a regular partition?

You can, but only in linux.

 

[Navid]

I am not going to set up software RAID.
My limited understanding of RAID tells me that I can set up RAID using the motherboard. So, it will be taken care of at a lower level than the OS.
The OS will not know that there is RAID.
Is this right or am I misinformed?

So, if I do it that way (using the motherboard), can I do a partial RAID 1?

 

[postmortemIA]

Originally posted by: Navid
I am not going to set up software RAID.
My limited understanding of RAID tells me that I can set up RAID using the motherboard. So, it will be taken care of at a lower level than the OS.
The OS will not know that there is RAID.
Is this right or am I misinformed?

So, if I do it that way (using the motherboard), can I do a partial RAID 1?

Os will see as one drive, yes, and then both drives are in RAID, there's is no way of letting part of drive be raid and part not with current motherboard-based RAID controllers.

 

[Nothinman]

Originally posted by: Navid
I am not going to set up software RAID.
My limited understanding of RAID tells me that I can set up RAID using the motherboard. So, it will be taken care of at a lower level than the OS.
The OS will not know that there is RAID.
Is this right or am I misinformed?

So, if I do it that way (using the motherboard), can I do a partial RAID 1?

For real RAID cards that's true, but for cheap onboard fakeraid it's not. All of the RAID functionality is done in the driver in Windows so it's done at the exact same level as software RAID, go ahead and setup the array in the BIOS and then when you install Windows give it the non-RAID driver and watch it display all of the drives separately instead of the array.

 

[Navid]

How can I set up a real RAID 1? Do I need a PCI card for that?
Where will the hard drive be connected to? To the PCI card?
Is there a PCI RAID card for SATA?

 

[Nothinman]

Yes, real RAID-anything needs a dedicated card. But RAID1 isn't usually worth buying a card for since it requires virtually 0 CPU time so when most people spend money on a card they do it either for the hardware xor engine to run RAID5 or RAID6 and/or the hotswap ability of the card.

 

[Navid]

Thanks for all the replies and the useful information.

I have a software that runs all the time on my Vista OS and creates incremental backups every day.
This is a backup of my data, which is about 4GB, which is on my first drive.
The backup is stored on my second drive.
On the second drive, I also store images of the OS, which is on the first drive.

On the second drive, I also store all my downloads (free utilities) and copies of all my purchased software CDs or DVDs. I also have my virtual CDs/DVDs on it.


If my first drive dies, I am covered thanks to the backups stored on the second drive.
But, if my second drive dies, I only have my current data on my first drive. I will lose all my history of backups, and all the OS images, and everything else.

How do you suggest I protect myself against a possible failure of my second drive?

I don't want to have yet another software running all the time to sync the second drive to a third.

Are there any other alternatives you can suggest?

 

[dclive]

Windows Home Server?

 

[JohnOfSheffield]

First of all, remember that RAID is not a backup solution, if something happens to the data apart from drive failure it will be gone.

Secondly, if you really need redundancy then get a hardware solution or run a decent software RAID setup, i wouldn't trust fakeraid solutions with any data at all, ever had a driver fail on you? Well in this case an unstable driver could mean that you have lost all data on your setup.

 

[JohnOfSheffield]

Originally posted by: Navid
Thanks for all the replies and the useful information.

I have a software that runs all the time on my Vista OS and creates incremental backups every day.
This is a backup of my data, which is about 4GB, which is on my first drive.
The backup is stored on my second drive.
On the second drive, I also store images of the OS, which is on the first drive.

On the second drive, I also store all my downloads (free utilities) and copies of all my purchased software CDs or DVDs. I also have my virtual CDs/DVDs on it.


If my first drive dies, I am covered thanks to the backups stored on the second drive.
But, if my second drive dies, I only have my current data on my first drive. I will lose all my history of backups, and all the OS images, and everything else.

How do you suggest I protect myself against a possible failure of my second drive?

I don't want to have yet another software running all the time to sync the second drive to a third.

Are there any other alternatives you can suggest?

4GB is one DVD, just back it up to a DVD and from there on do incremental backups to a DVD-RW. Same with the OS image (why would you need several images?) and everything else, DVD's are cheap enough today.

 

[RebateMonger]

Originally posted by: Navid
If I plug only one of the two drives to a motherboard and set it up as a simple drive (not RAID), will I not be able to access all the data?

It depends on the RAID1 design. I've pulled a single drive from a HighPoint RocketRAID controller, connected it to a standard IDE controller, and it booted right up.

I've read that other chipsets won't necessarily do that.