RAID 1 & RAID 5 or just RAID 5?

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YellowSnow

Limp Gawd
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I have a new HP Proliant ML350 G6 server that I'm preparing to be our new workgroup file server. It won't have a very heavy load, at least to begin with...we only have about 20 users and most of the time, they won't be accessing it.

I bought the server and six 250GB SATA drives which I connected to the RAID controller, a Smart Array P410i which is an 8 port hardware RAID controller.

Currently I have the controller configured to use two of the drives in a RAID 1 mirror for the OS and programs, and three drives in RAID 5 array, for the data that will be shared on the network. I planned to use the 6th HDD as a hot spare for both arrays, but it looks like you have to have one hot spare drive per array, so I'd have to buy another drive and the cage that allows you to add two more drives. Not the end of the world, but I'd like to work with what I already have.

I did install Windows 2003 Server already, but that's about as far as I've gotten. Should I wipe out everything and just make one RAID 5 array out of the first 5 drives and use it for the OS and the shared network folders? That way I'd only need one hot spare drive and it would be more economical regarding $/GB.

I'm just wondering if this would cause a big performance hit or if there are any other important factors I should be considering.

Also, I'm guessing not, but is there any way to preserve the OS install I already have and perform this setup change? I own Acronis, but not the Server version. No biggie if not. I haven't installed any programs or data yet. I was mainly just curious.
 
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I would just use one big RAID 5 array with a small OS partition. And use the rest of the space for Storage.
 
You might try installing the OS to a flash key and using the entire raid as storage. I just set one of these up at work (running linux) and it's beautiful :)
 
I'd say keep your setup the way it is now but with the hot spares. My reasoning:
- Should you ever need to reformat the OS or redo the RAID array for the OS, the data on the RAID 5 array is untouched
- Should either the RAID 5 or RAID 1 arrays fail, you'll usually have one up and running/available.
 
Darakian said:
You might try installing the OS to a flash key and using the entire raid as storage. I just set one of these up at work (running linux) and it's beautiful :)
Click to expand...

That's an interesting idea, but I want the programs and OS together and I want redundency. That flash key would be a single point of failure (SPOF), not to mention USB is slower than SATA...probably no biggie if you put your swap file on the array, but the SPOF is no good.
 
Danny Bui said:
I'd say keep your setup the way it is now but with the hot spares. My reasoning:
- Should you ever need to reformat the OS or redo the RAID array for the OS, the data on the RAID 5 array is untouched
- Should either the RAID 5 or RAID 1 arrays fail, you'll usually have one up and running/available.
Click to expand...

I agree that this would be best, but then I'd have to order the two drives and the proprietary extender cage and that means I can't use the generic hot swap cage I already have (for backups) due to space limitations, yada yada yada.

Let's assume I can't add more drives, the root of my question is will I see any significant performance loss by going to just one RAID 5 array? And I'm assuming it's true that going that direction with one hot spare is much safer than running only one hot spare for the data only, right?

I will definitely make a logical partition for just the OS and programs, to keep them seperate from the data.
 
What's your backup solution? How are you backing up your data? Assuming you are making backups I would keep the OS and programs on a separate RAID and shared files on your RAID 5 array. I wouldn't use a controller card's array to store my OS. That doesn't make sense to me. Controller cards should be system independent meaning if your mobo fries you can take the array and drop it in another system. I wouldn't like to carry the previous systems OS around should I need to move my storage.
 
cnick79 said:
What's your backup solution? How are you backing up your data? Assuming you are making backups I would keep the OS and programs on a separate RAID and shared files on your RAID 5 array. I wouldn't use a controller card's array to store my OS. That doesn't make sense to me. Controller cards should be system independent meaning if your mobo fries you can take the array and drop it in another system. I wouldn't like to carry the previous systems OS around should I need to move my storage.
Click to expand...

My backup solution is to simply schedule a file copy of the data to one of eight 500GB SATA drives that I already have, every night. I'm simply adding a hot swap cage to the Server and running a SATA cable to the motherboard. I'll use this app to safely swap in a new drive every night, without having to shutdown the server.

The two newest drives always go home with me at the end of the day, one is in the server in a hot swap drive cage, and the others are in a fire safe.

To further address your post, unfortunately this controller is soldered to the MoBo. There's no moving it to another system, unfortunately. But I do have a "next day" warrarnty and a backup server that I could always load last night's backup to.

I'm starting to wonder if the Mobo can do RAID 1. HP has already told me that the SATA ports on the Mobo are only for optical drives, but that's BS. I could add two SATA drives to my generic drive cage and load the OS on them if I could get RAID to work from the motherboard. I know I can choose to boot from the onboard SATA in the bios. Hmmm.
 
I don't see any way to use onboard RAID, and now that I think about it, I don't want to do that anyway.

I'm really leaning toward putting everything on one RAID 5 array. I'll make a logical partition for the OS and programs and one for the data.
 
HP support is telling me that by moving to all RAID 5, I'll actually see better performance, which makes sense given that the OS will now see RAID 5 performance which is better than RAID 1...I guess I was just operating from the standpoint that two is better than one, but that's not possible with this setup given the SPOF that the controller offers. I could add a 2nd RAID controller for the OS, but that's going to add money and time that I don't have.
 
YellowSnow said:
That's an interesting idea, but I want the programs and OS together and I want redundency. That flash key would be a single point of failure (SPOF), not to mention USB is slower than SATA...probably no biggie if you put your swap file on the array, but the SPOF is no good.
Click to expand...
That single point is the idea. We keep an image so we can swap out the flash drive alone if we ever need to. We're running with no swap (simple file server). And the speed of USB isn't much of an issue since the key is rarely read/written :)
 
Definitely an interesting idea. Is there free imaging software that works with Server OS's? I'd think you'd need it unless you want to set up the OS, programs and settings twice, manually.

Also, what particular USB keys are considered acceptable with regard to speed and dependability? I think you just revealed a great backup strategy for the OS partition.
 
dd, if you're not familiar it's an epic little linux program.
http://en.wikipedia.org/wiki/Dd_(Unix)
As far as drives go we bought two lexar fireflys (the explosive ones :D) and they run at about 30/10 MB/s for read/write. Since we're dealing with an image we can just drop it onto any 8+ GB flash drive in the future.

Server specs are
CentOS 5.4
4GB of ram
24TB raid in raid6
 
I believe that RAID 6 and 10 require an upgrade of the cache on the controller from 256MB to 512 and a cache battery and a license. So lame.

The good news is tha this new server/setup will be much better with regard to performance and safety than the current one.
 
YellowSnow said:
I believe that RAID 6 and 10 require an upgrade of the cache on the controller from 256MB to 512 and a cache battery and a license. So lame.

The good news is tha this new server/setup will be much better with regard to performance and safety than the current one.
Click to expand...


Thats the main point isn't it.
 
Better performance and safety is certainly the point. As is value.

We have a saying in car racing. Fast, cheap or reliable...pick two. :)
 
YellowSnow said:
Better performance and safety is certainly the point. As is value.

We have a saying in car racing. Fast, cheap or reliable...pick two. :)
Click to expand...

Nahhhh you can do all three, you just need looser definitions of "cheap", "fast" and "reliable" :p
 
I would put the OS & apps on a small RAID0(2 drives) or RAID5(3 drives) array and use a separate RAID5 of 3+ drives for data storage.

As for fault tolerance, set a backup of the System State on the RAID5 to run every once in a while.

Or do like above but 3 drives in RAID5 for system and 3 drives in RAID5 for storage. Striping with fault tolerance is the way to go.
 
DirectorC said:
I would put the OS & apps on a small RAID0(2 drives) or RAID5(3 drives) array and use a separate RAID5 of 3+ drives for data storage.

As for fault tolerance, set a backup of the System State on the RAID5 to run every once in a while.

Or do like above but 3 drives in RAID5 for system and 3 drives in RAID5 for storage. Striping with fault tolerance is the way to go.
Click to expand...

RAID 0 is never a good idea when up time and reliability is the goal.
 
DirectorC said:
I would put the OS & apps on a small RAID0(2 drives) or RAID5(3 drives) array and use a separate RAID5 of 3+ drives for data storage.

As for fault tolerance, set a backup of the System State on the RAID5 to run every once in a while.

Or do like above but 3 drives in RAID5 for system and 3 drives in RAID5 for storage. Striping with fault tolerance is the way to go.
Click to expand...

If this was a personal rig, sure, that would be the way to go...but it's a Server that a company will depend on.

Without buying an additional controller, there's no reason to have two arrays. When I set it up the way I did originally, I was thinking that the OS should have it's own array so that I could easily expand the data array when necessary. But it turns out this controller is pretty good at preserving existing partitions when restructuring the array, and there are free imaging solutions for server OS's (which I didn't know).

So, going to one RAID 5 array with a hot spare is going to give more more space, performance, and fault tolerance than the previous setup. I can always add a 2nd controller later for more fault tolerance.

BTW, I've decided against the USB thumb drive for the OS clone backups that I was thinking of based on Darakian's posts in favor of a similar strategy using a SATA drive. SATA is faster and cheaper and I already have extra SATA drives lying around that will work great. I can even make an extra clone and take it home in case the place burns down.
 
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