On Tue, Mar 01, 2016 at 05:50:09PM -0700, rodman@xxxxxxxxxxxxx wrote: > > It appears this is not an Mdadm bug but is in fact kernel/dash issue as > you noted, Piergiorgio. > > >From the bug tracker here: > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=787950 > > "This is a kernel/dash issue. In kernel 4.0, the md sysfs implementation > does not work with partial reads from /sys/block/md0/md/sync_action; > the read syscall returns the entire contents of the file even if you > try to read less. Dash has an inefficient implementation which reads > input one byte at a time, and fails when it hits the kernel > misbehavior." Just tested: dd if=/sys/block/md0/md/sync_action bs=1 count=1 On kernel 3.x I get "i", on kernel 4.x I get "idle"... :-) > > The work around is what you said. Substitute bash for sh at the > beginning of the script. Unfortunately that doesn't work for me as I > get this error when trying to run checkarray now: > "checkarray: E: /sys/block/md0/md/sync_action not writeable." Well, first check the permissions with: ls -l /sys/block/md0/md/sync_action Then make sure you're root, otherwise it will not be possible to write, of course. bye, pg > > I'll do some research to see what's that's about. I'm glad to know its > not a Mdadm issue per say. > > Rodman Frowert > > -------- Original Message -------- > Subject: Re: Checkarray doesn't seem to do anything > From: Piergiorgio Sartor <piergiorgio.sartor@xxxxxxxx> > Date: Tue, March 01, 2016 4:25 pm > To: rodman@xxxxxxxxxxxxx > Cc: linux-raid@xxxxxxxxxxxxxxx > > On Tue, Mar 01, 2016 at 02:57:21PM -0700, rodman@xxxxxxxxxxxxx wrote: > > Thank you for that information. My kernel is 4.2.0. > > I guess the problem is the same. > > > > > Is this it's intended behavior or is it simply a bug that has not been > > corrected? > > Well, I think it is a bug. > I'm not sure if "dash" bug or kernel bug. > I suspect "dash", since "bash" works... > > > > > I only bring this up as nearly all mdadm config tutorials at some point > > mention the checkarray function. They also point out that checkarray is > > also auto configured in the cron tab (cron.d) to run once a month. But > > of course, if checkarray doesn't work then people may think it is > > running once a month when it really isn't. > > Exactly! > I've some Ubuntu 14.04.x with old kernel, and one > with new kernel. > This one has a "weak" HDD in RAID (one / some blocks > waiting for relocation). > In my sytems the check occurs weekly, but it did not! > Tried from command line to no avail... > Debugging the script led to the previous result. > > I'm not sure, maybe someone should file a bug, but I > have not to much faith in Ubuntu md/mdadm support. > In the past they were slow or no reacting, and "mdadm" > was always an obsolete version (like it is in 14.04.x). > Maybe Debian could be a better place, not sure. > > bye, > > pg > > > > > > > Rodman Frowert -------- Original Message -------- > > Subject: Re: Checkarray doesn't seem to do anything > > From: Piergiorgio Sartor <piergiorgio.sartor@xxxxxxxx> > > Date: Tue, March 01, 2016 3:33 pm > > To: rodman@xxxxxxxxxxxxx > > Cc: linux-raid@xxxxxxxxxxxxxxx > > > > On Tue, Mar 01, 2016 at 02:09:44PM -0700, rodman@xxxxxxxxxxxxx wrote: > > > > > > Hello, > > > > > > I have a question as it pertains to the checkarray function of Mdadm. > > I > > > can't actually get it to do anything. I'm running Ubuntu 14.04.4 > > Server > > > LTS with the latest mdadm installed. I have a single RAID 1 mirror > > > configured and working properly near as I can tell. > > > > > > I can force a check if I issue "echo check > > > > /sys/block/md0/md/sync_action" as root. I can then see the status of > > > the check via /proc/mdstat or using the --detail switch on mdadm > > itself. > > > > > > However, nothing happens if I type in: > > > /usr/share/mdadm/checkarray -a > > > or > > > /usr/share/mdadm/checkarray -a /dev/mdX > > > or > > > /usr/share/mdadm/checkarray -as > > > > > > I've tried the commands as root and using sudo. The array sits idle > > > after all of the above commands. The only thing I can actually get > > > checkarray to perform is to give me the help output if I pass it -h. > > I > > > have attached, below, the current status of the mdadm managed array. > > > Doing some Googling I haven't been able to find anyone else that > > isn't > > > able to use the checkarray function so I must be doing something > > wrong. > > > > > > Any ideas? > > > > Well, yes, I've the same problem. > > > > Ubuntu 14.04.x with kernel 3.13, "checkarray" works. > > Ubuntu 14.04.x with kernel 4.11 (I think), "checkarray" > > does not work. > > > > The script runs with "dash" (not "bash") and it has > > a "read cur_status < something_from_sysfs" in order to check > > the array status. > > With kernel 3.13, the "read" returns the proper value, > > with kernel 4.11 (I think) the very same "read" exits > > the script without any message or else. > > > > One option is to use "bash", that is change the top > > of the script from: #!/bin/sh to #!/bin/bash > > > > Another is to change the "read", with a "cat", that is > > something like: cur_status=$( cat something_from_sysfs ) > > > > You can check yourself, there is only one "read" in > > the script (if I recall correctly). > > > > Hope this helps, > > > > bye, > > > > pg > > > > > > > > Rodman Frowert > > > > > > > > > > > cat /proc/mdstat shows: > > > ------------------ > > > rodman@nas:/usr/share/mdadm$ cat /proc/mdstat > > > Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] > > > [raid4] [raid10] > > > md0 : active raid1 sdc1[1] sdb1[0] > > > 5860389696 blocks super 1.2 [2/2] [UU] > > > ----------------- > > > > > > sudo mdadm --detail /dev/md0 shows: > > > ------------------ > > > rodman@nas:/usr/share/mdadm$ sudo mdadm --detail /dev/md0 > > > /dev/md0: > > > Version : 1.2 > > > Creation Time : Fri Feb 26 14:07:40 2016 > > > Raid Level : raid1 > > > Array Size : 5860389696 (5588.90 GiB 6001.04 GB) > > > Used Dev Size : 5860389696 (5588.90 GiB 6001.04 GB) > > > Raid Devices : 2 > > > Total Devices : 2 > > > Persistence : Superblock is persistent > > > > > > Update Time : Tue Mar 1 07:40:19 2016 > > > State : clean > > > Active Devices : 2 > > > Working Devices : 2 > > > Failed Devices : 0 > > > Spare Devices : 0 > > > > > > Name : nas:0 (local to host nas) > > > UUID : 4765e7df:0e1a6ad2:1321765f:a2d9f2c9 > > > Events : 164 > > > > > > Number Major Minor RaidDevice State > > > 0 8 17 0 active sync /dev/sdb1 > > > 1 8 33 1 active sync /dev/sdc1 > > > > > > ----------------- > > > -- > > > 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 > > > > -- > > > > piergiorgio > > -- > > 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 > > -- > > 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 > > -- > > piergiorgio -- piergiorgio -- 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
