Thanks Neil. Also, is there any way to find the current fault blocks being set? On Wed, Sep 28, 2011 at 6:08 PM, NeilBrown <neilb@xxxxxxx> wrote: > On Wed, 28 Sep 2011 17:59:49 -0700 Jojy Varghese <jojy.varghese@xxxxxxxxx> > wrote: > >> Thanks Neil. I tried setting my sda7 partition to generate write >> errors every 40 bytes(writing 1 byte at a time). I did : > > md doesn't see byte writes. It sees sectors or more - usually whole pages or > groups of pages. > >> >> 1. Create a array with: >> mdadm -C /dev/md/me0 -l faulty -n1 /dev/sda7 > > -C will write a superblock to /dev/sda7 which you don't really want. It > doesn't hurt, but I always used -B (--build) to avoid any metadata. > >> >> After this step I can see /dev/md127 and when i do a mdadm -D /dev/md127, i get: >> >> /dev/md127: >> Version : 1.2 >> Creation Time : Wed Sep 28 17:35:50 2011 >> Raid Level : faulty >> Array Size : 969410424 (924.50 GiB 992.68 GB) >> Raid Devices : 1 >> Total Devices : 1 >> Persistence : Superblock is persistent >> >> Update Time : Wed Sep 28 17:35:50 2011 >> State : clean >> Active Devices : 1 >> Working Devices : 1 >> Failed Devices : 0 >> Spare Devices : 0 >> >> Name : eng-dev16.lab.local:me0 (local to host eng-dev16.lab.local) >> UUID : 96f4be10:312f9574:f40107aa:d9f278ba >> Events : 0 >> >> Number Major Minor RaidDevice State >> 0 8 7 0 active sync /dev/sda7 >> >> >> 2. Set write fault level with: >> >> mdadm -G /dev/md/me0 --layout=wp40 >> >> >> >> After this when i write > 40 bytes into /dev/md127, i dont get any >> I/O errors. I am sure i am doing something wrong here. > > When you write to /dev/md127 it will just go into the page cache and > eventually be flushed to the device in one write. > Use O_DIRECT or O_SYNC and it will be flushed out more quickly, but always > write at least 512 bytes at a time. > > NeilBrown > > > >> >> >> Any help is much appreciated. >> >> Thanks >> Jojy > -- 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
