Honestly, I do not use the function of compressing multiple folders into multiple archives, so i am afraid i can't help you with that. Maybe admin can help u?

Good points, I didn't think of those.
Lack of recovery is a notable omission in the 7z format, although I do question the necessity of it these days (P2P applications do chunk hashing, transport streams and filesystems support checksumming). Perhaps it seems a little odd for a compression format, as the idea of compression is to remove redundancy whilst error recovery's aim is to increase redundancy. I guess you'd need to use an external application like PAR for this purpose, but I do take your point that integrated support may be nicer for some.

I've generally write scripts for more complex archive creation tasks, but taking a look at WinRAR it seems that it does have some handy ability to do stuff like exclude files or create multiple archives at a time. Isn't a format limitation though, so may be doable by another program. I know there are alternative archivers which compress to 7z, such as PeaZip, but I haven't really tried them so I don't know whether they have the ability to do this.

Good points - thanks for putting them forward.
I personally support 7z as it's free and open, has better compression (with the drawback that the 7-zip application doesn't always adaptively select  optimal compression methods whilst WinRAR does) and can be faster on many core machines as WinRAR can only use 2 threads. The format's support for chained filters is a pretty nice feature too.

Thanks for helping to explain. Your clarification is so much better. I am lazy =P.

whoaa.. thanks dude for give me such information, it's really worth reading it, from now on i think i'll use 7zip for compresing :)
sorry i'm not careful enough when read aniluv post..
@aniluv i expect that -__-, you already reply that many posts above after all, forgive this slug for not read your post carefully *bow hehee..