When are partitions helpful?

[Lamoni]

I was planning on doing a big upgrade soon and I am considering using 3 hard drives (2 in a Raid 0 array, and the third to back up important data) I know it isn't a very reliable backup, but I don't have anything so important that it would affect my livelyhood if it was lost. If I ever do, I'll burn it to CD.

I would use the Raid array for everything (OS, apps, games, data) and was wondering if there is any advantage to partitioning it. As a general rule I like to avoid partitions because I dislike having to remember what drive things are on, and I fear the following scenario:

I have a partitioned drive with 1.5 GB free and I want to install something that takes up 650 MB. Unfortunately I only have 500 MB free on three partitions so the app can't really be installed without a new hard drive.

That might never come up, but is there any problem to just having one partition? (I will most likely use two 80 gig HD's for a 160 GB partition and I'll be using NTFS)

The other puestion I have is with stripe and cluster size. I have heard that the default cluster size of 4Kb is often worst for Raid arrays, but I had always thought that larger clusters usually meant less efficient use of disk space... or was that only a concern for FAT32?

 

[HammerBot]

I know it isn't a very reliable backup

Well, I think this is a VERY reliable backup, since you need at least your backup drive AND one of you RAID drives to fail before you loose anything important. So go right on. Your data is safe.

I would use the Raid array for everything (OS, apps, games, data) and was wondering if there is any advantage to partitioning it

There are many advantages to partitioning. First of all I prefer my boot drive small (5 GB) and as the first partition. This ensures that system files always are located at the part of the drive that is accessed the fastest. Further, a number of small partitions makes defragmentation, undelete, recovery etc. much faster since you dont have to process the entire drive each time.

I have a partitioned drive with 1.5 GB free and I want to install something that takes up 650 MB. Unfortunately I only have 500 MB free on three partitions

Hopefully this is an uncommon situation, since you have a total of 160 GB. Further, it takes a while before you drive get that much filled. And if you ever get into such a situation, it is easy to rearrange partition sizes with eg. partition magic.

The other puestion I have is with stripe and cluster size. I have heard that the default cluster size of 4Kb is often worst for Raid arrays, but I had always thought that larger clusters usually meant less efficient use of disk space... or was that only a concern for FAT32?

Yes, I for one has stated somewhere in this forum that 4K is bad for RAID, since my tests showed that clearly. I recommend you test various combinations of cluster/stripesize to find the one that is optimal for you. Regarding clustersize, the waste is identical for NTFS vs. FAT(32) (and largely independent of drive size). In average you waste approximately 1/2*Clustersize pr. file you have on your disk. This is because that space is allocated in a multiple of one cluster.

 

[Napoleon]

Well, if you're already planning for 3 HDs, how about 4 HDs in RAID0+1 for great performance <i>and</i> reliability? Or alternatively just two HDs in RAID1? Just plain RAID1 would still give you improved read performance and plenty of reliability.

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[Lamoni]

Thanks for your input. I have now decided to go with partitions. Like you said, it is probably very unlikely that I will ever run into a situation that requires rearranging the partitions, but that still won't be hard. I just never thought of defragging and I would like to be able to defrag in a few hours rather than a few nights.

Now my question is how is it best to test for the best stripe size and cluster size? Do you format it as a secondary drive and time how long it takes to read and write large files from it? Or is there a simple program that I can use that can speed things along. It just seems like it would take a long time to reformat between each test when making about 9 tests. I am most likely showing my ignorance on the matter which is fine since my next upgrade will be the first time that I will actually set up a Raid array.

About the Raid 0+1 array: True, that would only require one more hard drive, but I am not made of money... and I don't need to back up the whole drive. Most of what I put on my computer I install from CD and therefore I don't back it up. Regarding Raid 1, the same thing is true from above where I don't need the entire hard drive backed up, but also I would much rather have 160 GB over 80 GB. And the read performance is increased with Raid 1, but not write. I basically want the best performance I can get with the least amount of money and still have enough data security to not start from scratch if something did happen.

 

[lhgpoobaa]

Indeed, if you are worried about reliability the addition of a 4th drive would mean you cold do an extreemly reliable RAID 0+1.
It may cost more now, but it will last for a long time. I know you want to.


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