clarification regarding RAID-0 vs RAID-linear . . .
Nodsu said:
Maybe you don't understand what RAID-0 is for. The real benefit of RAID-0 is speed, not disk space. Having data spanning (interleaving) both drives is good, because half of what you want will be served by one drive and the other half by the other drive. This means that you get your data 2x faster (in theory anyway).
If you want speed, at the price of bigger risk of complete data loss, you go for RAID-0.
If you want normalcy, you just partition two drives.
If you want to protect your data, at the price of losing disk space, you go for RAID-1 (and mirror the data).
upon further research I found out the situation I described is called "RAID-linear" and is the case where a virtual drive is created containing all the RAID'ed hard disk drives(HDD's).
this might be useful for huge files (files bigger than one of the hard drives), but I still see partitioning with RAID-linear as a potential bottleneck of performance do to the possibility of combining parts of different HDD's into one partition that has to be accessed by both drives in order to read the data.
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as you point out RAID-0 is an interleave between the HDD's, but I am still not clear how RAID-0's interleave system works.
does the first partition take up the outer rings of all the RAID'ed hard drives, the second partition the next inward set of cylinders, etc? or does this depend upon the RAID hardware controller?
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BTW, I became interested in this subject since I recently acquired a used Win XP Pro computer that had two HDD's setup using hardware RAID-0.
I used Partition Magic 8 to try to break the hardware RAID into something smaller than the single 500 GB = 2 x 250 GB partition that was on the machine.
unfortunately for me PM 8 crashed in the process and left the HDD data unaccessable.
I found a post on storagereview.net
http://forums.storagereview.net/ind...d=205485&mode=threaded&show=&st=&#entry205485
that says another person in a similar situation used PM 8 with a hardware RAID and had no problem.
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I found a post by Zolar1 on techspot.com
(
https://www.techspot.com/vb/topic1596.html, post # 14)
that gives a formula for determining optimum stripe and cluster size based upon average file sizes.
in my case the average for my previous system drive (C) is 303 kb and the average for my previous data drive (D) is 282 kb. (average file size can be found using Win XP's built in defrag program in analyze mode.)
the formula is
optimum stripe size =
(avg file size / 2 x # of RAID-0'ed HDD's)
and round down.
in my case with two HDD's I divide by four and round down to yield 64 kb as the optimum stripe size in both cases.
the other rule of thumb given is the optimum cluster size is half the stripe size so I would use 32 kb clusters in both cases.
if the numbers for stripe and cluster sizes had turned out to be different for the two partitions this means I would have to set up two different RAID-0 sets to achieve maximum results??? ie, stripe and cluster size are fixed for a hardware RAID-0 set and not fixed for a partition? is this correct?
joelwest