What drives for raid use

[taltamir]

this negates the risk of having one spinning disk failing and losing data on both

No it doesn't... SSDs DO fail, and RAID0 is still much more unreliable.
What you should do is use it for apps that need the speed, and have backups of whatever is on your RAID0 array...

 

[Dorkenstein]

RAID1, raid 1 is double the read speed (like raid0), same write speed as a single drive (unlike raid0 which has double write speed), and is the absolutely most reliable form of raid, bar none. It is also the easiest to upgrade, since drives simply come in pairs.
However, with RAID 1, 2 x 500GB drives = 500GB of storage. make sure to make seperate arrays for more drives than 2. So if you get 4 drives, don't make a raid1 of all 4, make 2 separate arrays, each one a raid1 array of 2 drives.

RAID1 is aka "mirroring"
RAID0 is aka "striping"

read: http://en.wikipedia.org/wiki/RAID

With RAID 1, does having the write speed of only one of your drives cause any bottlenecks, or is it really noticeable?

 

[taltamir]

With RAID 1, does having the write speed of only one of your drives cause any bottlenecks, or is it really noticeable?

that depends on the write speed of your drive. RAID1 writes the exact same file to both drives at the same time. So it will write at the speed of the slower drive. It reads half from each drive, so it will read at the double of their average. It is generally assumed you use two identical drives.

anyways, if you would have a bottleneck depends on the program you use, and the drive type (SSD vs spindle). But generally speaking write speed isn't a problem at all with RAID1 (many raid types and configurations could have significantly slower speed then than of a single drive, that is a problem... but RAID1 doesn't)

 

[Emulex]

There is a reason the 1gb flash-backed write cache is used these days. the ddr2/ddr3 ram helps immensely at random i/o and tweaking the modes (ratio read/write-back and linear/random) can make a huge difference.

what i don't get is why doesn't the o/s have more direct control of the i/o (or even application). If the app could hint to the o/s what its Motive is; the o/s could be aware of the storage subsystem and change its behavior.

I can think of only one app that does this . sqlos (aka sql server, virtual numa, buffers, lazy write, etc).

 

[Dorkenstein]

that depends on the write speed of your drive. RAID1 writes the exact same file to both drives at the same time. So it will write at the speed of the slower drive. It reads half from each drive, so it will read at the double of their average. It is generally assumed you use two identical drives.

anyways, if you would have a bottleneck depends on the program you use, and the drive type (SSD vs spindle). But generally speaking write speed isn't a problem at all with RAID1 (many raid types and configurations could have significantly slower speed then than of a single drive, that is a problem... but RAID1 doesn't)

You've almost completely sold me on RAID1. I might still go for RAID 0 because the stuff I am going to have on the drives isn't mission critical and I can back most of it up elsewhere. My other question is, can I image the content I am going to put on the RAID drives (games) and then when I get the two blank new drives running in RAID proceed to restore the imaged content to the RAID volume? Or should I re-install all the games by hand?

 

[FishAk]

Yes, but...


It's best to have your OS and all programs on the same partition, so you only have to deal with one image. I ran into trouble trying to restore two images- the OS partition, and a separate programs partition. It didn't work, and I don't know the reason for sure. Restoring the OS/program partition has worked as advertised for me on many occasions.


The other but...


It's important to not disturb your images by moving them or defraging them. The image needs to me original to be reliable. Make a partition on the inside edge – the slowest part- of your spinning disks for the sole purpose of storing images. This is a great place to store images, since you shouldn't need them often, and can afford the minor speed hit. As a bonus, it has the effect of also short stroaking the drive for additional performance. Than tell your defrag and backup tools to ignore that partition. You don't need to bother backing up the partition, since copies of images usually don't work. Make the partition big enough to save two or three images for each of your computers that have access to the drive. When you make changes to your OS partition, you can rotate in a new image, and dump one of the older ones after you verify the new image is good.

But generally speaking write speed isn't a problem at all with RAID1 (many raid types and configurations could have significantly slower speed then than of a single drive, that is a problem... but RAID1 doesn't)

Yah, he's almost got me convinced too. I'm running a 4 disk RAID 01, and I'm tempted to switch to a couple RAID 1 arrays and see if I can tell any difference in real world performance. Most of the files I write are several MB, and a few approach a couple GB, so there are a lot of sequential writes.

 

[Dorkenstein]

Well, my OS is on a completely separate drive. The games are on a separate drive that is almost full (640gb). I just want to image the games drive to a backup drive and then when I replace the 640gb with the 2 Samsungs in RAID, restore the image to that.

 

[FishAk]

I do hope it works for you. Like I said, it didn't work out for me, and I ended up having to do a compete install. I had three image sets, so I don't know why it didn't work, and I never spent any time trying to figure it out.


Given the way you're already set up, you don't have a choice. The only other option is to do a fresh install, and that's also the worst that will happen if you can't restore the images. If you do have to do a fresh install, I suggest setting up the programs on the OS partition. I never saw the advantage having them separate, and it was a hassle.

 

[Dorkenstein]

So... I should just re-install all my games manually? I'm getting a little confused.

 

[FishAk]

If you can image your games partition, and also image your OS partition, you can try to restore both the images on your new setup. I'm saying that did not work for me, but I don't know the reason it didn't work. Possibly it would work for you, so you might as well try it. If you're only other option is to do a complete install, you will only loose a small amount of time- and gain some knowledge- by trying it, before doing a complete install because you find it doesn't work for you also.


What I'm saying is that IF it doesn't work, and you are forced to re-install- consider making the new install all on one partition.


It's possible you can get a valid image of your OS to load, but just can't get the games to stick. In that case, you would only need to re-install the games. If you have to reload only the games, I would still put them with the OS.

 

[Dorkenstein]

I think I understand now. When you make a RAID array, do you have to reinstall windows? I got confused when you mentioned imaging my OS drive, because I have no plan to do that. If I absolutely have to because of making a RAID array, that's another story.

 

[FishAk]

Depending on the programming of the controller you use, it's possible that you may be able to build an array without loosing data on the member disks. Do not plan it this way. Plan to have the controller delete everything on the disks you use for the array. This means you need an image of your OS partition, unless you intend to completely start from scratch, reload Windows and all the programs from scratch. Your data can simply be copied from your backup drives to the array after the array is built, so you don't need an image for that.


Keep in mind that when you build the array, everything on the member disks is at risk, especially when you build the array but at all times after that also. There is no substitute for a valid backup. With a good backup- including an image of your OS-, when you build the array,if everything on the member disks gets wiped out- it's no big deal to simply reload it. So plan to loose all data from the member disks when you build your array. If you don't loose it, great- but the risk is very high.

 

[Emulex]

dude just do what we do; run a solo SSD and a big ass drive then back both up?


raid is not cool; it is a necessity for work. It is a pain in the ass to take care of.

did you think about when you combine the two drives if the new combination will be aligned? can you re-align online? can you change stripe size to optimize to Your application?

i'd be prepared to do a few scorched earth installs. take the drive you have and put it to the side; pick up a couple of RE3's and give it a shot; the results are highly dependent on the controller(software/hardware). i've yet to see anything built on a consumer board be any good. the P410i that is built onto the hp server motherboards is pretty awesome but still there are the rules you must follow.

 

[Dorkenstein]

Referring to me, Emulex? I'd like nothing more than to buy a solo SSD that can fit nearly a terabyte of games and mods. Does such a thing exist? Doubtful. Could I afford it? Absolutely no way.

 

[taltamir]

Referring to me, Emulex? I'd like nothing more than to buy a solo SSD that can fit nearly a terabyte of games and mods. Does such a thing exist? Doubtful. Could I afford it? Absolutely no way.

reread his post, he said a solo SSD AND a big ass drive.
so, say an 80GB OS SSD and a 2TB drive running solo (not in raid), and backup from both of those somewhere else. Which is a good idea. (back it up to a NAS RAID1)

 

[Dorkenstein]

I read that part. The large mechanical drive is doable for me, which I why I didn't mention it in the same post as an SSD. My OS is already on a 64gb SSD, so if I get another one I want it to be at least 100gb. It sounds like it's best for me to pass on a RAID setup.