Robert
Excellent. It works like a champ, after changing llapi_get_name() to
llapi_getname().
Thanks much. If we meet up at a conference some day, I owe you dinner.
John
On 7/18/2016 6:13 PM, Read, Robert wrote:
Hi John,
The initial string in the OSC name is the filesystem name and the long
hexadecimal number at the end is the client ID. The client ID is
specific to the mount point that “owns” the OSC, and typically changes
each time the filesystem is mounted. It is there to differentiate
devices when the same filesystem is mounted multiple times.
You can retrieve both of the values by passing the mount directory to
llapi_get_name(). This function returns a string with filesystem name
and client ID in the format “FSNAME-ID". You can split the string on
the ‘-‘ to extract those values, and then use them construct the right
name for the current OSC being used for that file on that particular
mountpoint.
Note, like the client ID, the OSC name is specific to that mount
point. The actual OST name is just FSNAME-OST####.
robert
On Jul 18, 2016, at 15:22 , John Bauer <[email protected]
<mailto:[email protected]>> wrote:
I will restate the problem I am having with Lustre.
With my I/O instrumentation library, I want to use
*llapi_file_get_stripe*() to find the OSTs that a file of interest is
striped on and then monitor only those OST's using files in the
directory /proc/fs/lustre/osc. This needs to be done
programmatically, and in a general sense, with potentially only a
relative path name.
*llapi_file_get stripe*() yields
lmm_stripe_count: 1
lmm_stripe_size: 1048576
lmm_pattern: 1
lmm_layout_gen: 0
lmm_stripe_offset: 12
lmm_oi.oi_fid *0x**194aa*
*obdidx* objid objid group
*12* 31515860 0x1e0e4d4 0
If I use *obdidx=12=0xc *to find the OST in directory
/proc/fs/lustre/osc, I get multiple OSTs as there are multiple file
systems with an ost of index 12 ( note that obdidx is decimal and
entries in */proc/fs/lustre/osc* are hexadecimal, so we are looking
for OST000c ).
%ls -ld /proc/fs/lustre/osc/*OST000c*
dr-xr-xr-x 2 root root 0 Jul 18 14:31
/proc/fs/lustre/osc/nbp1-OST000c-osc-ffff88090509f000
dr-xr-xr-x 2 root root 0 Jul 18 14:31
/proc/fs/lustre/osc/nbp2-OST000c-osc-ffff881038061c00
dr-xr-xr-x 2 root root 0 Jul 18 14:31
/proc/fs/lustre/osc/nbp6-OST000c-osc-ffff88084c405400
dr-xr-xr-x 2 root root 0 Jul 18 14:31
/proc/fs/lustre/osc/nbp7-OST000c-osc-ffff8807a8e1d400
dr-xr-xr-x 2 root root 0 Jul 18 14:31
/proc/fs/lustre/osc/nbp8-OST000c-osc-ffff88078339b800
dr-xr-xr-x 2 root root 0 Jul 18 14:31
/proc/fs/lustre/osc/nbp9-OST000c-osc-ffff8807833a5400
So I need to figure out which directory entry applies to the OST of
my file of interest.
I looked at the inode for clues. I did an stat() of the file to get
dev_t st_dev=0xcc5d43c2
ino_t st_ino=0x2000311ed0194aa
I notice the *lov_user_md->oi_fid=0x0194aa,* populated by
*llapi_file_get_stripe*(), is reflected in the lower part of *stat.st
<http://stat.st>_ino=0x2000311ed0194aa*. My question is, "Does the
remainder of st_ino, *2000311ed*, give me any clue as to which OST I
should use out of */proc/fs/lustre/osc*?" The same question applies
to the OST's objid=0x1e0e4d4and the file's st_dev=0xcc5d43c2.
Because I know a priori that the file is in the lov nbp2, I know I
need to find
/proc/fs/lustre/osc/*nbp2-OST000c-osc-ffff881038061c00.***What does the
*ffff881038061c00 *represent?It is the same value for all OST's in a
given lov, so I am guessing it is lov related.*
*
There are over 1200 OST on the node, so I want to minimize the number
that I instrument.
Any information that would shed some light on this would be greatly
appreciated.
John
--
I/O Doctors, LLC
507-766-0378
[email protected]
_______________________________________________
lustre-discuss mailing list
[email protected] <mailto:[email protected]>
http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
--
I/O Doctors, LLC
507-766-0378
[email protected]
_______________________________________________
lustre-discuss mailing list
[email protected]
http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
