On Fri, Jul 15, 2016 at 6:05 PM, Zdenek Kabelac <zkabelac@xxxxxxxxxx> wrote: > Dne 15.7.2016 v 14:15 Navin P.S napsal(a): > >> On Fri, Jul 15, 2016 at 5:21 PM, Mikulas Patocka <mpatocka@xxxxxxxxxx> >> wrote: >>> >>> >>> >>> On Fri, 15 Jul 2016, Navin P.S wrote: >>> >>>> Resend .. >>>> >>>> On Thu, Jul 14, 2016 at 7:55 PM, Navin P.S <navinp1912@xxxxxxxxx> wrote: >>>>> >>>>> Hi, >>>>> Can i do dd if=/dev/zero of=/dev/mapper/dmo count=20 ? where dmo is >>>>> a dm snapshot origin created through dmsetup command. Instead of >>>>> /dev/zero i can write valid devices. >>>>> >>>>> I could create the dmo through some lvm2 commands. >>> >>> >>> lvcreate -s >>> >>>>> Is direct write >>>>> with 4k (page size values ) allowed when it is mapped to 2 block >>>>> devices in linear mode ? >>>>> >>>>> >>>>> Regards, >>>>> -- Navin >>>> >>>> >>>> I'm seeing OOM followed by reboot of host machine. >>>> Does this mean this device cannot to exported to containers for writing >>>> ? >>> >>> >>> The snapshot driver requires 32 bytes of memory for one chunk (the chunk >>> size is selected with the "-c" switch to lvcreate). You should set system >>> memory according to that. >>> >>> Mikulas >>> >>>> -- Navin >>>> >> >> >> >> >> Are origin devices readonly ? >> >> When i do dd if=/dev/zero of=/dev/mapper/ff count=10, it kills all the >> process says OOM. >> >> How do you go about debugging this ? I'm running 4.7.0-rc7+ . >> >> >> root@vm-xenial-foo:~# dmsetup info >> Name: cryptie4-ff >> State: ACTIVE >> Read Ahead: 256 >> Tables present: LIVE >> Open count: 0 >> Event number: 0 >> Major, minor: 251, 0 >> Number of targets: 2 >> >> Name: ff >> State: ACTIVE >> Read Ahead: 256 >> Tables present: LIVE >> Open count: 0 >> Event number: 0 >> Major, minor: 251, 1 >> Number of targets: 1 >> >> root@vm-xenial-foo:~# dmsetup status >> cryptie4-ff: 0 102400 linear >> cryptie4-ff: 102400 122880 linear >> ff: 0 102400 snapshot-origin >> root@vm-xenial-foo:~# > > > Hi > > Maybe you should have started with reading documenation for snapshot target > ? > > linux/Documentation/device-mapper/snapshot.txt > It nowhere mentions that origin device is readonly. It says writes go to COW device and then you can merge it back. Can you please paste the snippet ? -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
