On Mon, March 2, 2009 1:42 pm, Brian Manning wrote: > I've been running a MD three-drive raid-5 for a while now with no problems > on a CentOS 5.2 i386 box. I've attempted to add a fourth drive to the > array yesterday & grow it. This is where things got ugly.... > > It began the reshape as expected, some hours later I rebooted the box for > another reason entirely, forgetting about the reshape that was still going > on. But it was a clean shutdown process and md stopped just fine. So I > wasn't too worried about it, I knew it was just pick up again once it > booted. > > After startup the kernel found the md, said it was to resume the > reshape... then it came time for the kernel to mount root.. and hung > scanning for Logical Volumes, I left it for over an hour, it never > proceeded past this stage. Disk io light was off, nothing going on. > > My entire OS save /boot is on the raid-5, split across several LVM2s > inside that md device. It's always worked fine for me in the past. > > But now LVM is hanging on boot, I can't even get into single mode or > anything like that. So I bring out the boot disc and go into rescue mode. > > I check the raid status, everything looks okay, so I manually start the MD > again from the boot cd, and that fires up as expected, however.... when I > look at /proc/mdstat... the speed is 0KB/sec, and the ETA is growing by > 100's of minutes a second. > > I let this go for about 2 hours, and nothing ever happens, speed is 0, > diskio light is off, nothing is happening. I notice that your array has a chunksize of 1024K. That is big enough to cause an issue that was only resolved in mdadm-2.6.8, which I suspect you aren't using. If you echo 1024 > /sys/block/md0/md/stripe_cache_size it might spring to life. I think the 1024 is right, but if it doesn't work try a larger number (e.g. 8192) just in case I got the math wrong. And: no, you cannot go back to a 3 drive array. The transformation is currently one-way. NeilBrown -- 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
