Best raid setup to go with

By ingeborgdot ยท 13 replies
Sep 14, 2006
  1. I have a 250 sata and just got a matching one. I have had just one for over a year now but think maybe I would like to do an raid setup. Is it possible now? If so, what is the best raid setup?
  2. LipsOfVenom

    LipsOfVenom TS Rookie Posts: 160

    Most popular are RAID 0 and RAID 1. People like to use RAID 1 because it mirrors data to prevent loss. RAID 0 runs faster, but has a higher risk of losing data. Your choice actually, but I prefer RAID 1 for myself, seeing as I usually don't care about the 1 or so millisecond speed difference.
  3. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 441

    What if I added a third hd? Does that give me another option?
  4. Blakhart

    Blakhart TS Rookie Posts: 353

    Raid setups have tradeoffs, usualy in one of two ways. Either you can have more space with less reliabilty (raid0), or less total space with more reliability(raid5), total number of drives for each being the same.

    My game system, for example, has 2 10000rpm scsi drives and a hardware raid controller, they work pretty well together in aid0, but don't really give the performance expected in many cases. Raid, of most any type, will never give the lowest disk access times, wich is what everyone should really be concerned with rather than transfer rates or any other criteria, no lie. If I benchmark the array with iometer or hdtach, it benches quite a bit slower than if I benched with atto or sandra, iometer and hdtach being more "real world" and less "hopefull" than atto or sandra, I have given up 4ms access time to get an aid0 array with two times or more access time, easily measured. 8ms might as well be forever to a computer. Ok more to the point, raid is something that in my case can fail on me quite easily, one drive fails and the whole thing is gone, and it does not have double the performance of each drive individualy. If you do a raid1 with your two (or more) drives, you will get slightly better reads, probably slower writes, but you now have half the disk space. If your data is that valuable there's your answer, do raid1 if you can, but I prefer disk space over the unavoidable risk of data loss we all face.

    What should I have done to maximise disk space rather than aid0? Just run both disks without any raid at all, one devoted to the os and storage, and the other for all the apps/programs, with a pagefile on each drive. The reason one might want pagefiles on each disk is because windows, and Linux for that matter, can write to one drive's pagefile while it reads from the other. Or vice versa. Write to both, read from both, whatever. This is beneficial in all sorts of ways. As well, having one disk more or less dedicated to the demands of the os while the other disk attends to apps reduces disk latency and disk subsystem contention further. Systems set up this way run very smoothly.

    I will say this about raid stripe sets, if you do video editing or work with generaly huge files, aid0 can be of benefit if you don't mind the risk of data loss. I say aid0 as the 0 level has no redundancy. If you just use the system to browse, play games, burn cds, etc, you will be far better served by running those two drives as I have stated above. Much more reliable this way. Now on to another aspect of raid technology: most all onboard (non-scsi) raid chips, and most (non-scsi) add on pci cards use the cpu to perform all their functions, your cpu has to do all the work. My raid card has it's own cpu, memory, and os (more or less) to perform all those disk functions. Now if you have a super-powerfull cpu you don't have to be too concerned with this cpu usage, but it is there, all the time.

    But no matter, do as you like. You can always learn from trying various raid levels and whatnot, I am certain, though, that you will find things pretty much as I have laid them out to you. But most people, me included, will be better served by running the disks separately, not part of an array. I intend on reconfiguring my drive system as independant disks, no array at all. Giving up lower access time just to have an aid0 array isn't really worth it when all I care about is games. In the games I play, latency is everything.
  5. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 441

    Thanks. I do video editing but not all the time and not a lot. I will probably just keep it as two seperate hd.
    I just need a better understanding about what you were talking about for using the two as seperates. You say one disc as os and storage and the other apps.
    My understanding was that the apps need to be on the same disc or partition as the os. If not could you explain to me how you plan to partition and put it all on the two? I would be greatly in your debt for a little more education on the matter.
    Right now I have one 250gb hd. I have it partitioned into 3 parts. One partition is os and programs, one is storage of my documents, video etc, other for backup. I was going to use the 3rd partition as an image to backup the os part but haven't had the time and am not sure what to do.
    I have the os partitioned at 31mb but only have 9.1gb left. I have some big programs I need and have installed. Do you have some pointers for me on this? Could I use the 3rd part and partition that back to the 1st partition using any special program? Is there anyway to get the 3 partition into the 1st one?
  6. Blakhart

    Blakhart TS Rookie Posts: 353

    Ok that's seems to be a pretty fair partition strategy, especialy if the os gets hosed. Since your apps and data are on another partition they are safe if you nuke the os part and reinstall. If I had a single drive and wanted data security I would do it that way, but along these lines: 9.5gb os partition, upon wich only the os lives, along with the pagedfile. Then a apps/data partition of whatever size I wanted, and rather than a data partition I would use folders in that same partition as apps. Now the reason why I prefer folders over partitions is I have always had a performance hit running multiple partitions. It has something to do with the os having to traverse partitions on the same drive to get what data it needs. Simple as that. But the way you're doing it is practical for security of data. By the way, no app I know of must be on the same drive or partition as the os to function. never ran into that one, although it could exist, there seems to be no absolutes as far as computers go. Sometimes you just gatta punt. Now as to the question regarding moving partitions into one, or creating multiple partitions out of one, I have never liked any software that fudged with partitions. I prefer to do a clean install on a totaly zerod disk (zerod = running an app, such as "Darik's boot and nuke" that writes zeros to the entire drive, wich should also flag any bad spots found, and I only zero used drives, new should not need it, and while I am on zeroing, I have _always_ gotten a performance increase from zero'd drives over just letting an os install format the drive) and let the os do all the parting. That's just me though.

    Now if you want to run the drives as separates, not part of an array, just install the os on one disk taking that whole disk, and format the other as one partition. Probably end up as C: (os) and F: (apps/data). With E: being an optical drive. Something like that.

    Ok now with the os on one disk, you also make a folder called DL on the os drive: this folder will catch all your downloads. Divide up the DL folder with sub folders to hold related downloads, system drivers in a system folder, game downloads into the game folder, etc. If you don't organise you will quickly have a real mess. Kinda like my bedroom. Oy. Then on the os drive make a folder called Data or Storage, in wich you can make folders for each type of data. Most any and all stored/backup data should go here. This data storage folder is for storage, not continously needed data such as something like a scratchfile, a scratchfile should go on the apps drive, because we want to split the workload between the drives. Keep in mind the os drive is always busy, always, because the os lives there and is always paging memory blocks to and from disk. So storage on that drive is the best way to make use of that wasted space on the os drive, my biggest os installs are like 4gb, on a 250gb disk that's a lot of wasted space. So we put data there. No harm to the os performance at all as the data is seldom accessed. Now since we are on wasted space, I am not certain this holds true anymore, but any time you reached the half full point on a drive formatted NTFS you would see reduced performance. And you'd be lucky if you could defrag that drive. I keep my drives as bare as I can.

    Ok on the Apps drive you first create a pagefile before you add any folders or apps. This is done by right clicking my computer/properties/advanced/performance/advanced/at the bottom click the "change" button/then select the apps drive. It is best to let Windows control the size of the pagefile. Less complications this way. Then follow the notices the os gives you regarding what you have done and there you are, the proud owner of a dual disk system with multiple page files. Now you go and make the app folders and even a data folder to take up the room the apps leave. Make sub folders as needed to keep things organised. Heat and serve.

    Rules of pagefiles: One pagefile per physical disk only. Each physical drive should have a pagefile. If you put multiple pagefiles on the same physical disk you are probably hurting performance. There' s no sense in that at all. Buuuut, if you have a scratchfile for some video editing app, place it on the apps drive somewhere, it is basicaly a pagefile but one only used by that app, not the entire system. Keep in mind that Windows uses an algorithm (al gore rythm) to determine wich drive is fastest and to page to that one when it can. If you add old slower drives to a newer system and place a pagefile on them, it might end up unused. Buuut, if Windows needs to page right now, it will use any pagefile it can write to or read from.

    NOTE: Multiple pagefiles do not add miracle level performance, but you should notice a more responsive system, and a smoother running one. Your apps will love you for it.

    Ok I hope that answers some of your questions re disk strategies. They are only my suggestions, you can vary them quite a bit and still have good disk performance. Oh yeah almost forgot, if these are pata IDE drives, not sata, they need to be on separate IDE channels so they can operate at the same time. If they are on the same channel, only one disk can talk to the os at a time, kinda makeing everything we just did pointless. They should also be the masters on their respective channels. With sata you have none of these worries at all. Feel free to ask my input on anything you'd like.
  7. jobeard

    jobeard TS Ambassador Posts: 11,177   +989

    if you truely want the BEST, then you need a SCSI RAID controller and attached devices :)
  8. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 441

    So with the apps I already have can I move them to the new drive without any problems or do I need to uninstall them and reinstall them on the new drive? What can I do to get the apps to the new drive? If I move them that will free up much of the space on my first partition.
    So my setup would be #1 hard drive
    partition one os
    partition two documents, video, etc
    partition three backup
    drive #2 apps and ?

    I will read your post over again to make sure of everything.
  9. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 441

    If you put it in simple terms?
    How would it look to you?
    If I were going to leave my hard drive I already have formatted and am using the way it is with the three partitions what would you do?
    Hard disc one

    Partition 1 31GB

    Partition 2 178GB

    Partition 3 31 GB

    Hard disc two
  10. Blakhart

    Blakhart TS Rookie Posts: 353

    I would leave the os on the first drive/partition, and use the second partition on that drive for storage, then put the DL folder on the 3rd partition.

    On the second drive I would make the drive one partition and add a swapfile, then use folders for apps and further storage. Normaly you can cut/paste your currently installed apps to another disk, and then redirect the shortcuts if you need to. I have never had any probs moving apps to different drives or partitions save for some old vb apps that were flaky at best anyway.

    But me, I would save everything from your first disk, nuke that disk with a drive zero app, and then set the entire system up as I have stated in my previous posts.
  11. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 441

    So what you are saying is to reinstall my os on the first drive and my apps on the second.
    I know what you are saying but I have so many big programs that it would take me at least 10 or more hours to get them all reinstalled.

    If I don't do that I would like to just make it a little simpler and have my storage on disc one along with the os. My os partition is 31gb with only 9gb left. Isn't that a bad ratio? I am thinking about using partition magic or something like that to take and make my 3rd partition part of the 1st for a 62gb partition which would leave me well over half of the partition full. Am I making any sense. On my other drive I will use that for video storage as I do some editing. I want to make it a little easier to do. I understand what you are talking about for the other but I don't think I will see too much speed loss with my way.
    I am just not sure of using partition magic though. I have my stuff backed up and wonder how it would be done as I have never done it before.
  12. Blakhart

    Blakhart TS Rookie Posts: 353

    I haven't used pm in years, so I will be of little help with it, but you seem to have a grasp on what you'd like to do, jump in, but first make backups....
  13. ingeborgdot

    ingeborgdot TechSpot Paladin Topic Starter Posts: 441

    But it can be done with pm can't it?
  14. Blakhart

    Blakhart TS Rookie Posts: 353

    Yeah I think pm can do it. Try it after you back up the vitals.
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