raid 0 stripe size? space loss?

[zulu]

Hey guys I'm having a tough time trying to decide whether I should put a couple drives I just got in raid-0. Thought I'd see if any of you have some experience with this.

I've done a lot of reading about it, but one thing I'm unclear about is the stripes. I can set the stripe size to 4K, 8, 16, 32, 64, or 128 with my on-board promise controller. Here's the thing, I seem to remember something about if you write a file that is less than the size of the stripe, you lose space. Is this right? Of course now I can't find the information again... For example, if I write a 8K file and I'm set up with 128K stripes, do I lose 120K when the stripe is sent to one of the drives?? I know this isn't much, but repeat it a thousands of times...and...seems it could add up to a lot. BUT maybe I'm totally wrong about this?

(i read that larger stripes are better for video editing, so I'd like to make the stripe size bigger than, say, 8K...but I'm also going to have windows, games, and other various on the same setup...so trying to find the best "compromise" here...)

[zulu]

by the way one reason i post here instead of a big "well known" tech forum is because every time I post something about raid-0 it just turns into a big argument between the forum regulars on whether it's worth it or not lol... bottom line is i'd like to give it a go, but if i'm going to be wasting tons of space...then i don't think i will

[LA_MERC_T4rg3T]

This may help

http://www.storagereview.com/guide2000/ref/hdd/perf/raid/concepts/perfStripe.html

http://www.anandtech.com/storage/showdoc.html?i=1491&p=5

[LA_MERC_Spark]

Nice post Toby.

[zulu]

This may help

http://www.storagereview.com/guide2000/ref/hdd/perf/raid/concepts/perfStripe.html

http://www.anandtech.com/storage/showdoc.html?i=1491&p=5

hey thanks for the links, i've read those both before...but not quite as closely as I did this time :p It makes a little more sense now, but, they deal with "perfect" file sizes.

take one of anad's example, for instance. they talk about splitting up a 8192KB file using a 1024KB stripe size. This would evenly split into 8 blocks, which makes sense.

here's where my question is....say i'm writing a file that is 8200KB -- this would need 8 blocks + _______??? would it need a whole extra block to hold the remainder of 8KB, with the other 1016KB in the block unused? or does it just sit on one of the disks, not "in a block"? make sense?

thanks

[zulu]

...finally found it... :p

"Another problem with stripes in general is that each stripe holds at maximum one file – and any extra space in the stripe that isn’t full, gets wasted.
(112KB for every 16KB written to a 128KB stripe, 128-16=112)
(Wastage gets worse if you have huge stripes, and lots of small files)"
http://forums.amd.com/index.php?showtopic=10335

sigh...guess i'm just going to keep them as independent drives