TUNEDASD(8)

📦 version 2.44.1, in opensuse-leap 16.0

🌸 TUNEDASD(8) — the DASD glow-up tool

okay so bestie, welcome to tunedasd, from section 8 of the System Manager's Manual. She's a little utility that adjusts tunable parameters on DASD devices, and honestly she ate. Let's get into it 💅

✨ NAME ✨

tunedasd — a tool to adjust tunable parameters on DASD devices, no cap.

🎀 SYNOPSIS 🎀

tunedasd [OPTION] COMMAND device

🦋 DESCRIPTION 🦋

So tunedasd is a tool to adjust tunable parameters on DASD devices. Lowkey iconic. You can use it to modify the status of the device and to adjust some performance relevant settings.

The DEVICE is the node of the device (e.g. '/dev/dasda') or a list of devices separated by a space character. Yes, a whole list, she's flexible like that 🫶

Following functions are supported:

  • Get and reset the performance statistics profile per device.
  • Get and set the caching mode of the storage server. This is only available for ECKD devices, because it is implemented using ECKD Channel Program commands.
  • Reserve/Release/Unconditional Reserve a device. This is only available for ECKD devices, because it is based on the Control Unit functions.
fr fr, if tunedasd is called without parameter, it prints a short usage information and exits. She's not gonna guess what you want, bestie 😭

💖 OPTIONS 💖

  • -v or --version — Print version information, then exit. A little "hi, it's me" moment ✨

🌈 COMMANDS 🌈

  • -h or --help — Print usage information, then exit. Your map, your guide, your emotional support flag 🎀
  • -g or --get_cache — Get current storage server caching behavior. Just a lil peek 👀
  • -c or --cache <behavior> — Define caching behavior on storage server. The following caching behaviors are currently supported by modern Enterprise Storage Servers (ESS):
    • normal ('Normal Cache replacement'),
    • bypass (Bypass Cache),
    • inhibit (Inhibit Cache Loading),
    • sequential (Sequential Access),
    • prestage (Sequential Prestage),
    • record (Record Access)

More details about caching can be found in the 'Storage Control Reference' of the attached storage server. iykyk 📚

  • -n or --no_cyl <n> — Number of cylinders to be cached (only valid together with --cache). Like, she only works in tandem with --cache, that's her bestie 💜
  • -S or --reserve — Reserve device. Claiming her as yours 🔥
  • -L or --release — Release device. Letting go, growth era 🦋
  • -O or --slock — Unconditional reserve device.
Note: Use with care, this breaks an existing reserve. Not me warning you twice, she is DRAMATIC and she will break whatever reserve is already there 💀
  • --enable-stats — Enable performance statistics globally.
Note: Same as "echo 'set on' > /proc/dasd/statistics"
  • --disable-stats — Disable performance statistics globally.
Note: Same as "echo 'set off' > /proc/dasd/statistics"
  • -P or --profile — Print profile info of device.
Note: Profile info must be available and enabled in the kernel to get valid results out of the profile commands. Enable statistics via --enable-stats. No stats enabled, no cute data, bestie 🙈
  • -Q or --query_reserve — Query the current reserve status of the device. The following states are defined:
    • none: The device is not reserved.
    • implicit: The device is not reserved, but there is a contingent or implicit allegiance to this Linux instance.
    • other: The device is reserved to another operating system instance.
    • reserved: The device is reserved to this Linux instance.

More details about reserve/release can be found in the 'Storage Control Reference' of the attached storage server. Go read her ⭐

  • -I or --prof_item <row> — Print single profile item data row (without header). Following rows are supported:
    • reqs (# of dasd I/O requests),
    • sects (# of 512Byte sectors),
    • sizes (Histogram of sizes),
    • total (Histogram of I/O times),
    • totsect (Histogram of I/O times per sector),
    • start (Histogram of I/O time till ssch),
    • irq (istogram of I/O time between ssch and irq),
    • irqsect (istogram of I/O time between ssch and irq per sector),
    • end (Histogram of I/O time between irq and end),
    • queue (# of req in chanq at enqueuing)
  • -R or --reset_prof — Reset profile info of device. Clean slate, main character energy 👑
  • -p or --path_reset <chpid> — Reset a channel path <chpid> of a selected device. A channel path might be suspended due to high IFCC error rates or a High Performance FICON failure. Use this option to resume considering the channel path for I/O. Giving that path her second chance 🌸
  • --path_reset_all — Reset all channel paths of the selected device. The channel paths might be suspended due to high IFCC error rates or a High Performance FICON failure. Use this option to resume considering all defined channel paths for I/O. All of them. Every single one. Group hug 🫶
  • -s or --copy-pair-swap <copy_pair> — Swap the copy roles of the specified copy pair. The <copy_pair> has to be a comma separated pair of PRIMARY,SECONDARY where PRIMARY is the old primary device that will become a secondary automatically. The old SECONDARY device will become the new primary device. Both devices have to be online for this operation to succeed. Role reversal, it's giving character development 💫

🔥 EXAMPLE 🔥

  1. Scenario: Get profile info for a device.
tunedasd -P /dev/dasdc
tunedasd -PI irq /dev/dasdc
  1. Scenario: Set device caching mode to 1 cylinder 'prestage'.
tunedasd -c prestage -n 1 /dev/dasdc
  1. Scenario: Reset failed channel path with CHPID 45
tunedasd -p 45 /dev/dasdc
  1. Scenario: Swap copy pair 0.0.9700 and 0.0.9740
tunedasd -s 0.0.9700,0.0.9740 /dev/dasdc

🌟 SEE ALSO 🌟

dasdview(8), dasdfmt(8), fdasd(8) — go say hi to the whole squad 🧚

aaaand that's the page, bestie 💖 she's from s390-tools, dated Apr 2006, and she still slays. mwah 🎀

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