[dm-devel] Multipath Statistics
Lan
transter at gmail.com
Wed Apr 13 17:41:49 UTC 2005
Hi all,
Thought it would be a good time to bring up a discussion on the type
of statistics that dm-multipath would find useful, e.g. for a load
balancing path selection algorithm or for users. This is a list of
statistics provided by an IBM multipathing product. (The discussion of
how to gather these type of statistics would also require another
discussion). Any thoughts/suggestions?
Per Path Information:
- Number of times the path was selected for I/O
- Number of I/O errors on this path
Per Adapter Information :
- The number of times this adapter was selected for I/O
- The number of errors on all paths attached to this adapter
- The number of paths attached to this adapter
- The number of functional paths attached to this adapter (i.e.
Exclude failed or offline paths)
Path Performance Information (more specific breakdown):
Total Read I/O: Total number of completed read requests
Total Read Sector: Total number of sectors that have been read
Total Write I/O: Total number of completed write requests
Total Write Sector: Total number of sectors that have been written
Active Read I/O: Total number of read requests in process
Active Read Sector: Total number of sectors to read in process
Active Write I/O: Total number of write requests in process
Active Write Sector: Total number of sectors to write in process
Maximum I/O: The maximum number of active I/O requests
Maximum Sector: The maximum number of active sectors to read or write
Transfer Size:
<= X , (X = {512, 4K, 16K, 64K}) The number of I/O requests received
whose transfer size is X bytes or less
> 64K The number of I/O requests received whose transfer size is greater than 64KB
Adapter Performance Information:
** identical to Path performance information except no "Transfer Size'" info
Thanks!
Lan
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