humm head seek time? only testing to know if it will be decreased or not the idea is: if md update metadata veryoften you should consider put most i/o files near metadata sectors to don't lose time with head positioning real difference of metadata position? maybe some bootloaders can't boot with md metadata at start/end of disk/partition. if you don't use this md device to boot, you don't need to worry about it, any position will work, i don't know about growing array size problems about meta data positioning, but i think you don't need to worry about this too 2011/3/24 hank peng <pengxihan@xxxxxxxxx>: > 2011/3/24 Roberto Spadim <roberto@xxxxxxxxxxxxx>: >> i think you will have no problems with location of metadata, there's >> some versions of metadata, at start at end.. check your mdadm --create >> command > > yes, I found that option. If I choose to put metadata on the start > area of a disk, disk's head seek time will be decreased, right? > > So, is there someone in this list to tell me what is real difference > when putting meta data on start or end of a disk? > >> what information at metadata is/was wrong? can you get it? or just i/o error? >> some months ago i had two broken harddisks, the disk start to read >> from position 0 to position X without problem, but when it get at a >> position where disk was crashed (real crashed, the disk hit the floor) >> the array start to resync (maybe a disk report) it was a raid10 array. >> maybe you have problem at physical layer (disk with problem). >> i don't know what informations md update at metadata, but i think that >> there's some last write counter/last write timestamp to sync what >> mirrors is more recent in a broken array start, (this information can >> be found with others developers in this list) >> >> 2011/3/23 hank peng <pengxihan@xxxxxxxxx>: >>> Hi, guys: >>> I found that when disk errors happened, it is more likely to locate in >>> md super block area. Kernel messages are like this: >>> end_request: I/O error, dev sda, sector 1953525000 >>> md: super_written gets error=-5, uptodate=0 >>> In some cases, I check if disk is really failed using 'dd' command and >>> found that it is OK for read and write on those sectors. >>> >>> I know that md super block information is located in the end of a >>> disk, but is it related with this problem? Is it safer to put md super >>> block in the start area of a disk? >>> >>> >>> -- >>> The simplest is not all best but the best is surely the simplest! >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >> >> >> >> -- >> Roberto Spadim >> Spadim Technology / SPAEmpresarial >> > > > > -- > The simplest is not all best but the best is surely the simplest! > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
