On Sat, 2011-10-15 at 21:59 +0200, Helmut Hullen wrote: > Hallo, Martin, > > Du meintest am 15.10.11: > > > RAID-0 and valuable (?) data does not match together. > > I know. The data isn't valuable. It's *.mpeg2 from DVB-T, repeated at > least every two years. It's a kind of old LP or old VHS cassette. > > But that doesn't solve the problem with errors on one of the disks. I > don't like to throw away a disk if it has (perhaps) repairable read > errors. I'd like to use a tool like "badblocks". Well, lets take a look at the state of your drive. Install smartmontools, and run 'smartctl -A /dev/sdX'. One a properly operational drive, you'll see these: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0 First things first. If the VALUE of Reallocated_Sector_Ct is less than or equal to THRES, then your drive is garbage; all of the reallocation space has been used. This means many errors have occured, and more will keep happening. Get it replaced ASAP. If the RAW_VALUE of Reallocated_Sector_Ct is above 0, then the drive has in the past dynamically reallocated some sectors - i.e. it has had errors, but they have been repaired. The Current_Pending_Sector value is interesting. It counts the number of sectors which have had read errors, but have not been remapped internally in the drive, because it couldn't recover the data using error correction. These result in Read errors in the OS - this is probably what you are seeing. If you have pending sectors, causing the drive to reallocate them is very simple. Write data (any data) over the sector in question - the drive will then remap it onto the spare area to do the write. (The easiest way is to do something like dd if=/dev/zero of=/dev/sdX; but if you know the exact sector number, "hdparm --write-sector" can remap it quickly.) Keep in mind, though - if you have a single reallocated sector on a drive, it means that the drive medium is deteriorating. It's very likely that you will have additional failures in the future, resulting in more IO errors and lost data. For your sanity, I recommend replacing a drive as soon as you see any one error on it. -- Calvin Walton <calvin.walton@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
