Lustre discuss - Aug 2008 - question with mount.lustre truncating device name

Hello,

      We are trying to get a 1.6.5.1 lustre system up and running.  We 
are using udev to map out our fiber channel devices.

We have the following disk /dev/sdb with the scsi_id below.
[root at abe-io07 ~]# ls_fc_luns
HBA  210000e08b0db5cb  host1
210000e08b0db5cb 0x200200a0b80f4498 1:0:0:0 sdb
3600a0b80000f449700000000487dc46a
[root at abe-io07 ~]

The udev rule looks like this:
[root at abe-io07 ~]# grep "ost_l_01" /etc/udev/rules.d/20-local.rules
BUS="scsi", SYSFS{vendor}="IBM",
SYSFS{model}="1742",
PROGRAM="/sbin/scsi_id -g -u -s /block/%k ", 
RESULT="3600a0b80000f449700000000487dc46a",
NAME="disk/fc/fastt6e_0"
SYMLINK="disk/lustre/ost_l_01"
[root at abe-io07 ~]#

The device is there properly named:
[root at abe-io07 ~]# ll /dev/sdb
brw-------  1 root root 8, 16 Aug  5 07:10 /dev/sdb

[root at abe-io07 ~]# ll /dev/disk/fc/fastt6e_0
brw-rw----  1 root disk 8, 16 Aug  5 12:10 /dev/disk/fc/fastt6e_0

[root at abe-io07 ~]# ll /dev/disk/lustre/ost_l_01
lrwxrwxrwx  1 root root 15 Aug  5 12:12 /dev/disk/lustre/ost_l_01 ->
../fc/fastt6e_0

We did a mkfs.lustre on it and it said it was successful(we used the 
/dev/disk/lustre/ost_l_01 device for the format).  But when we 
try to mount the device we get the following error:

  [root at abe-io07 ~]# mount -v -t lustre 
/dev/disk/lustre/ost_l_01 /lustre/local/ost_l_01
arg[0] = /sbin/mount.lustre
arg[1] = -v
arg[2] = -o
arg[3] = rw
arg[4] = /dev/disk/lustre/ost_l_01
arg[5] = /lustre/local/ost_l_01
source = /dev/disk/lustre/ost_l_01 (/dev/disk/lustre/ost_l_01), target = 
/lustre/local/ost_l_01
options = rw
mounting device /dev/disk/lustre/ost_l_01 at /lustre/local/ost_l_01, 
flags=0 options=device=/dev/disk/lustre/ost_l_01
warning: No such file or directory, device /dev/disk/fc/fastt stat 
failed
/sbin/mount.lustre: unable to set tunables for /dev/disk/lustre/ost_l_01 
(may cause reduced IO performance)mount.lustre: mount 
/dev/disk/lustre/ost_l_01 at /lustre/local/ost_l_01 failed: Input/output 
error
Is the MGS running?
[root at abe-io07 ~]

The warning: ... the device name is getting truncated.

It looks like from mount_lustre.c that any device name that contains a 
numeric digit in the device name will get truncated.

         /* The name of the device say ''X'' specified in /dev/X
may not
          * match any entry under /sys/block/. In that case we need to
          * match the major/minor number to find the entry under
          * sys/block corresponding to /dev/X */
         dev = real_path + src_len - 1;
         while (dev > real_path) {
                 if (isdigit(*dev))
                         *dev = 0;
                 dev--;
         }

         rc = stat(dev, &stat_buf);
         if (rc) {
                 if (verbose)
                         fprintf(stderr, "warning: %s, device %s stat
failed\n",
                                 strerror(errno), dev);
                 return rc;
         }

Was looking for some suggestions on getting around this issue.

Thanks,
Chad

On Wed, 2008-08-06 at 07:16 -0500, Chad Kerner wrote:
> Hello,
> 
>       We are trying to get a 1.6.5.1 lustre system up and running.  We 
> are using udev to map out our fiber channel devices.
...
> It looks like from mount_lustre.c that any device name that contains a 
> numeric digit in the device name will get truncated.
Indeed.

You can change the NAME="disk/fc/fastt6e_0" in your udev rule to match
the device naming convention that is being assumed by mount.lustre and
that''s that the only digits in the last path component are postfixed
and
identify partitions.

If you don''t install your own udev rule, what does the kernel name that
device by default?  Does it match the assumption that mount.lustre is
making?

b.

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