RAW device question on Solaris
A user asked how to reliably tell whether an existing raw device on Solaris 10 is in use by a process, or whether it already contains user data, since dd alone didn't answer the question. Suggestions from the list: dump the first part of the device with dd (e.g. bs=256k count=4) and inspect it with od -c to see if data is present; use Solaris' format command to check each device; use lsof to see which processes have the device open; and monitor activity with iostat -Mx or DTrace scripts such as iotop. The poster said he would try them, but no definitive answer was recorded.
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Hi everyone. Does anyone know of a full-proof way of determining whether or an existing raw device on a Solaris 10 machine is currently being used by a process? or better yet...if it contains any user data (IE: it was used at some point and was written to?). I thought I could use dd but it looks like that does not answer the question. If anyone has any ideas I would appreciate it.
One way to see what's on the partition: (as root) dd if=/dev/raw/partition_name of=/tmp/disk_dump bs=256k count=4 od -c /tmp/disk_dump | more will let you look at the 1st MB of that partition. Bob ----- Original Message ----- From: "WILL LANDSTROM" <willlandstrom@yahoo.com> To: ids@iiug.org Sent: Tuesday, October 27, 2009 11:26:57 AM GMT -05:00 US/Canada Eastern Subject: RAW device question on Solaris [17773] Hi everyone. Does anyone know of a full-proof way of determining whether or an existing raw device on a Solaris 10 machine is currently being used by a process? or better yet...if it contains any user data (IE: it was used at some point and was written to?). I thought I could use dd but it looks like that does not answer the question. If anyone has any ideas I would appreciate it. ******************************************************************************* Forum Note: Use "Reply" to post a response in the discussion forum.
This may be kind of tedious but you could use the format command and then select each device (one at a time) to see if the device is in use or not. MM
There is also a tool - I don't think it comes with the core Solaris install, called 'lsof' that might help you. MM
Hey Bob. Thanks. How's everything going?
Mike. Thanks for the suggestions. I will check them out.
- lsof : show open files/devices - iostat -Mx 5 1000 | awk '$2 != "0.0" || $3 != "0.0"' show the I/O for each device every 5 seconds... more information: man iostat - iotop A nice shell (DTrace) I get here: http://www.brendangregg.com/DTrace/iotop
I Forgot, others useful shell for solaris to monitoring your server/instance usage: http://www.prefetch.net/articles/solaris.dtracetopten.html check the Number 5: Figuring out how much I/O is generated per process