* why disk errors are more likely to happen on md super block area? @ 2011-03-24 1:34 hank peng 2011-03-24 3:48 ` Roberto Spadim 0 siblings, 1 reply; 4+ messages in thread From: hank peng @ 2011-03-24 1:34 UTC (permalink / raw) To: linux-raid 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! ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: why disk errors are more likely to happen on md super block area? 2011-03-24 1:34 why disk errors are more likely to happen on md super block area? hank peng @ 2011-03-24 3:48 ` Roberto Spadim 2011-03-25 2:27 ` hank peng 0 siblings, 1 reply; 4+ messages in thread From: Roberto Spadim @ 2011-03-24 3:48 UTC (permalink / raw) To: hank peng; +Cc: linux-raid 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 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@gmail.com>: > 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@vger.kernel.org > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: why disk errors are more likely to happen on md super block area? 2011-03-24 3:48 ` Roberto Spadim @ 2011-03-25 2:27 ` hank peng 2011-03-25 3:42 ` Roberto Spadim 0 siblings, 1 reply; 4+ messages in thread From: hank peng @ 2011-03-25 2:27 UTC (permalink / raw) To: Roberto Spadim; +Cc: linux-raid 2011/3/24 Roberto Spadim <roberto@spadim.com.br>: > 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@gmail.com>: >> 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@vger.kernel.org >> 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: why disk errors are more likely to happen on md super block area? 2011-03-25 2:27 ` hank peng @ 2011-03-25 3:42 ` Roberto Spadim 0 siblings, 0 replies; 4+ messages in thread From: Roberto Spadim @ 2011-03-25 3:42 UTC (permalink / raw) To: hank peng; +Cc: linux-raid 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@gmail.com>: > 2011/3/24 Roberto Spadim <roberto@spadim.com.br>: >> 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@gmail.com>: >>> 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@vger.kernel.org >>> 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@vger.kernel.org > 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@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2011-03-25 3:42 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2011-03-24 1:34 why disk errors are more likely to happen on md super block area? hank peng 2011-03-24 3:48 ` Roberto Spadim 2011-03-25 2:27 ` hank peng 2011-03-25 3:42 ` Roberto Spadim
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