05545c92db
This patch implements tape statistics in the st module via sysfs. Current no statistics are available for tape I/O and there is no easy way to reuse the block layer statistics for tape as tape is a character device and does not have perform I/O in sector sized chunks (the size of the data written to tape can change). For tapes we also need extra stats related to things like tape movement (via other I/O). There have been multiple end users requesting statistics including AT&T (and some HP customers who have not given permission to be named). It is impossible for them to investigate any issues related to tape performance in a non-invasive way. [jejb: eliminate PRId64] Signed-off-by: Shane Seymour <shane.seymour@hp.com> Tested-by: Shane Seymour <shane.seymour@hp.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: James Bottomley <JBottomley@Odin.com>
110 lines
3.3 KiB
Plaintext
110 lines
3.3 KiB
Plaintext
What: /sys/class/scsi_tape/*/stats/in_flight
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Date: Apr 2015
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KernelVersion: 4.2
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Contact: Shane Seymour <shane.seymour@hp.com>
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Description:
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Show the number of I/Os currently in-flight between the st
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module and the SCSI mid-layer.
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Users:
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What: /sys/class/scsi_tape/*/stats/io_ns
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Date: Apr 2015
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KernelVersion: 4.2
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Contact: Shane Seymour <shane.seymour@hp.com>
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Description:
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Shows the total amount of time spent waiting for all I/O
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to and from the tape drive to complete. This includes all
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reads, writes, and other SCSI commands issued to the tape
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drive. An example of other SCSI commands would be tape
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movement such as a rewind when a rewind tape device is
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closed. This item is measured in nanoseconds.
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To determine the amount of time spent waiting for other I/O
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to complete subtract read_ns and write_ns from this value.
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Users:
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What: /sys/class/scsi_tape/*/stats/other_cnt
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Date: Apr 2015
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KernelVersion: 4.2
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Contact: Shane Seymour <shane.seymour@hp.com>
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Description:
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The number of I/O requests issued to the tape drive other
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than SCSI read/write requests.
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Users:
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What: /sys/class/scsi_tape/*/stats/read_byte_cnt
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Date: Apr 2015
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KernelVersion: 4.2
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Contact: Shane Seymour <shane.seymour@hp.com>
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Description:
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Shows the total number of bytes requested from the tape drive.
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This value is presented in bytes because tape drives support
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variable length block sizes.
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Users:
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What: /sys/class/scsi_tape/*/stats/read_cnt
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Date: Apr 2015
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KernelVersion: 4.2
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Contact: Shane Seymour <shane.seymour@hp.com>
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Description:
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Shows the total number of read requests issued to the tape
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drive.
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Users:
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What: /sys/class/scsi_tape/*/stats/read_ns
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Date: Apr 2015
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KernelVersion: 4.2
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Contact: Shane Seymour <shane.seymour@hp.com>
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Description:
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Shows the total amount of time in nanoseconds waiting for
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read I/O requests to complete.
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Users:
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What: /sys/class/scsi_tape/*/stats/write_byte_cnt
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Date: Apr 2015
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KernelVersion: 4.2
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Contact: Shane Seymour <shane.seymour@hp.com>
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Description:
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Shows the total number of bytes written to the tape drive.
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This value is presented in bytes because tape drives support
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variable length block sizes.
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Users:
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What: /sys/class/scsi_tape/*/stats/write_cnt
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Date: Apr 2015
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KernelVersion: 4.2
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Contact: Shane Seymour <shane.seymour@hp.com>
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Description:
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Shows the total number of write requests issued to the tape
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drive.
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Users:
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What: /sys/class/scsi_tape/*/stats/write_ms
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Date: Apr 2015
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KernelVersion: 4.2
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Contact: Shane Seymour <shane.seymour@hp.com>
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Description:
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Shows the total amount of time in nanoseconds waiting for
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write I/O requests to complete.
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Users:
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What: /sys/class/scsi_tape/*/stats/resid_cnt
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Date: Apr 2015
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KernelVersion: 4.2
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Contact: Shane Seymour <shane.seymour@hp.com>
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Description:
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Shows the number of times we found that a residual >0
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was found when the SCSI midlayer indicated that there was
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an error. For reads this may be a case of someone issuing
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reads greater than the block size.
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Users:
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