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[OT?] RAID 0 chunk size question...

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    [OT?] RAID 0 chunk size question...

    What do you think is the best chunk size to use for gaming? Given the choices are 8, 16, 32, 64, or 128? I just got two new WD HDD's and at first I had a RAID 0 with a 64 chunk size, and noticed no increase in map load times when compared to without RAID. Then, I tried a 16 chunk size (current). Still, I'm seeing no decrease in load times. When I had my two maxtor HDD's setup on a RAID 0, the load times decreased DRAMATICALLY, only I can't remember what it's settings were. My new SATA WD RAID 0 array is seemingly performing as fast as my old single Maxtor IDE hard drive, without RAID.

    Any opinions? Thanks in advance,
    Shmenge

    #2
    A general rule is that higher 'chunk' sizes give better performance, at the expense of being less efficient on space. With today's large capacity drives, it shouldn't be an issue. Go for the max.

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      #3

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        #4
        Originally posted by senshu
        A general rule is that higher 'chunk' sizes give better performance, at the expense of being less efficient on space. With today's large capacity drives, it shouldn't be an issue. Go for the max.
        'nuff said.

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          #5
          would anyone else like to comment on this? I could use all the input I can get. So far it looks like I'm going to go with a 128 array. Anyone else have anything they'd like to add?

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            #6
            Originally posted by ShmengeTravel
            would anyone else like to comment on this? I could use all the input I can get. So far it looks like I'm going to go with a 128 array. Anyone else have anything they'd like to add?
            Listen to senshu. Nothing else to add.

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              #7
              what does he mean by being "less efficient" on space? What, would I have to defrag a lot?

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                #8
                The "chunk" size, which I assume is the same as "allocation unit" size, is the minimum amount of data that can be allocated for file space. Say, for instance, you had a file that that was 128,001 bytes in size, and the chunk size was 128. The file system would allocate 1,001 chunks for this file, but the file only uses 1 byte in the last chunk, so 127 bytes are wasted and can't be used for anything else. Now suppose you had 1,000 files (you actually have 10s, or even 100s of thousands of files on a typical hard drive). With a chunk size of 128, it's possible that 127,000 bytes of data could be wasted if each file only used 1 byte in the last chunk allocated to it.

                If the chunk size was 64 then this same situation would only waste 63,000 bytes (about half). So why wouldn't you want to use the smallest chunk size? Because the larger the chunk size the less a file will get fragmented. Also, and probably most importantly, because the larger the chunk size, the faster the file can be manipulated because larger chunks are being moved at a time.

                Actually 128 is pretty small. I think my HD is formatted with 2048 0r 4096 byte chunks (or allocation unit size).

                EDIT: I have no idea if the chunk size is what's causing your performance problems. It's possible that there is another bottleneck somewhere, and knowing nothing about SATA or RAID setups I'm afraid I can't help.

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                  #9
                  Originally posted by ShmengeTravel
                  what does he mean by being "less efficient" on space? What, would I have to defrag a lot?
                  Sorry, but I don't think that you can defrag a RAID 0 array:noob:

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                    #10
                    Originally posted by da ghost
                    Sorry, but I don't think that you can defrag a RAID 0 array:noob:
                    Really? Why not? And wouldn't the performance degrade over time because of fragmentation?

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                      #11
                      Originally posted by Psycho Dad
                      The "chunk" size, which I assume is the same as "allocation unit" size, is the minimum amount of data that can be allocated for file space. Say, for instance, you had a file that that was 128,001 bytes in size, and the chunk size was 128. The file system would allocate 1,001 chunks for this file, but the file only uses 1 byte in the last chunk, so 127 bytes are wasted and can't be used for anything else. Now suppose you had 1,000 files (you actually have 10s, or even 100s of thousands of files on a typical hard drive). With a chunk size of 128, it's possible that 127,000 bytes of data could be wasted if each file only used 1 byte in the last chunk allocated to it.

                      If the chunk size was 64 then this same situation would only waste 63,000 bytes (about half). So why wouldn't you want to use the smallest chunk size? Because the larger the chunk size the less a file will get fragmented. Also, and probably most importantly, because the larger the chunk size, the faster the file can be manipulated because larger chunks are being moved at a time.

                      Just to add that this is a worst case scenario.

                      I always found RAID 0 to be completely overrated especially for gaming.

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                        #12
                        Yes, you can (and should) defrag a RAID 0 array.

                        No, there is no major benefit for gaming. Only very I/O intensive apps (video editing, etc.) will benefit from RAID 0 these days. Even that's questionable...my raided Raptors fly, once they get spinning. :bored:

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                          #13
                          Originally posted by Psycho Dad
                          Really? Why not? And wouldn't the performance degrade over time because of fragmentation?
                          It's because the data is fragmented no matter what (the definition of RAID 0. It it was defragmented, it would actually be slower :haha::haha::haha: ). The RAID controller just can't handle fragmentation and rearrangement of data like that. besides, no matter how fragmented it gets (ok maybe not THAT fragmented) it still will be faster that than standard SATA drives.

                          Unless there are new controllers out there...if there are, you need to TELL ME!!!!

                          EDIT: well, senshu's got one...
                          EDIT2: and st trooper... looks like I'm outdated...

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                            #14
                            Just to confirm, you can defrag a RAID 0.

                            I also find defragging to be overrated. I defrag about once a year.

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                              #15
                              Originally posted by st_trooper
                              Just to add that this is a worst case scenario.

                              I always found RAID 0 to be completely overrated especially for gaming.
                              Naw, I always make sure my files are a multiple of chunk size + 1.

                              Yes, it was the worse case, but I was just trying to make a point. Like I said, 128 seems really small. With chunk sizes of 2048 or 4096 quite a lot of space can be wasted, especially if you have lots of small files. If you mostly do video editing then you'd want to make the chunk size as large as possible. I'm sure there is some optimum size for the average gamer type person.

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