![]() ![]() It's true that a typical i/o operation, like reading a file, does check if the data that was read is actually correct. But as with other RAID systems, it is recommended to schedule periodic scrubs. And it is an active scan, it won't detect future errors - the goal of a scrub is to find and fix errors on your drives at that point in time. regular read operations (this doesn't just apply to BTRFS only):Īs pointed out by Ioan, a scrub can take many hours, depending on the size and type of the array (and other factors), even more than a day in some cases. Update: Improved grep as suggested by Michael Kjörling, thanks.Īdditional notes on scrubbing vs. Otherwise, it'll run in the background and you would have to remember to check the results manually as they would not be in the email. The -B option will keep the scrub in the foreground, so that you will see the results in the email cron sends you. In addition, with advanced filesystems like BTRFS (that have checksumming) it's often recommended to schedule a scrub every couple of weeks to detect silent corruption caused by a bad drive. Obviously, you would test such a scenario (for example by causing corruption or removing the grep) to verify that the email notification works. This will check for positive error counts every hour and send you an email. So you could create a simple root cronjob: /sbin/btrfs device stats /data | grep -vE ' 0$' I am sure someone with better knowledge will correct me / elaborate on this.In addition to the regular logging system, BTRFS does have a stats command, which keeps track of errors (including read, write and corruption/checksum errors) per drive: # btrfs device stats / Since the partitions had already been assembled by the kernel, the normal array assembly which uses nf was skipped.Ĭalling sudo update-initramfs -u tells the kernel take a look at the system again to figure out how to start up. When the kernel assembles the arrays, it does not use nf. The kernel assembled the arrays prior to the normal time to assemble the arrays occurs. I am far from an expert on this, but my understanding is this. In short, I chopped my /etc/mdadm/nf definitions from: ARRAY /dev/md1 metadata=1.2 name=ion:1 UUID=aa1f85b0:a2391657:cfd38029:772c560e I found the answer here, RAID starting at md127 instead of md0. So once again, I think all is good and I reboot.Īgain, after the reboot, /dev/md1 is /dev/md126 and /dev/md2 is /dev/md127? Ls -la /dev | grep md returns: brw-rw- 1 root disk 9, 1 Oct 30 11:26 md1īrw-rw- 1 root disk 9, 2 Oct 30 11:26 md2 Sudo mdadm -assemble -verbose /dev/md2 /dev/sdb2 /dev/sdc2 Sudo mdadm -assemble -verbose /dev/md1 /dev/sdb1 /dev/sdc1 ![]() ![]() Ls -la /dev | grep md returns: drwxr-xr-x 2 root root 80 Oct 30 11:18 mdīrw-rw- 1 root disk 9, 126 Oct 30 11:18 md126īrw-rw- 1 root disk 9, 127 Oct 30 11:18 md127Īll is not lost, I: sudo mdadm -stop /dev/md126 Md127 : active (auto-read-only) raid1 sdb1 sdc1 Ls -la /dev | grep md returns: brw-rw- 1 root disk 9, 1 Oct 30 11:06 md1īrw-rw- 1 root disk 9, 2 Oct 30 11:06 md2Īfter the reboot, /dev/md1 is now /dev/md126 and /dev/md2 is now /dev/md127? ![]() # instruct the monitoring daemon where to send mail alerts # automatically tag new arrays as belonging to the local system # auto-create devices with Debian standard permissionsĬREATE owner=root group=disk mode=0660 auto=yes alternatively, specify devices to scan, using # by default (built-in), scan all partitions (/proc/partitions) and all # Please refer to nf(5) for information about this file. Which I appended it to /etc/mdadm/nf, see below: # nf Sudo mdadm -create -verbose /dev/md2 -level=mirror -raid-devices=2 /dev/sdb2 /dev/sdc2 I created a RAID with: sudo mdadm -create -verbose /dev/md1 -level=mirror -raid-devices=2 /dev/sdb1 /dev/sdc1 ![]()
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