>> No. With modern hard drives, no filesystem should pay any >> attention to badblocks - it's all handled in the drive firmware. > ext4 supports this, Also JFS also supports bad-block avoidance, but only at 'mkfs' time and JFS does this for legacy reason: Linux JFS supports this because it is a port of JFS/2 from OS/2 which was a port of JFS version 1 from AIX in 1990. > and is a relatively modern filesystem released in December > 2008. It is just a retread of 'ext3' which itself was a recycling of 'ext2' which was in turn a clone of the 4BSD FFS, and we are talking of design decisions taken in 1982-3, not 2008. > While it could be argued that this is for legacy support, It is for legacy support. Once upon a time a drive's controller was the main CPU itself, and the kernel had to manage bad block sparing (as well as rotational layout and track buffering). That was up to around 20-30 years ago :-). > This feature still adds value (see below). It adds value if one underestimates typical disk drive failure modes. It is quite irritating even for me that a drive with way less than 1% bad blocks becomes effectively unusable, but long experience tells me that once a drive starts to grow defects to the point that manufacturer spare sectors run out there is usually a reason for it and sooner than later it will be almost completely unusable. [ ... ] > The use case is simple: What if I want to have more goodblocks to > correct for badblocks than Seagate thinks I should have? The answer is also simple: if you think you know better than Seagate, or if you think that Seagate deliberately allocates too few spare sector, you ask Seagate for custom firmware that allocates more of a disk capacity for spares. I suspect that with an order of at least 100,000 drives they will be happy to help. :-) > Eg, a charity or poor student wanting to get the most out of their > old hardware. If it is your itch, and you think you know better than the rest of the industry, scratch your itch: send patches :-). Other people know that usually keeping decaying drives in use is fairly pointless. Legend is that USSR computer engineers perfected that art though, but they worked in special circumstances. For a similar example look at the BadRAM and similar modules: https://help.ubuntu.com/community/BadRAM http://rick.vanrein.org/linux/badram/ They haven't become that popular... :-) -- 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
