DASDFMT(8)

📦 version 2.44.1, in opensuse-leap 16.0

💖 NAME 💖

Okay bestie, meet dasdfmt(8) from the System Manager's Manual — this is the page all about formatting of DASD (ECKD) disk drives. 💅✨

✨ SYNOPSIS ✨

dasdfmt [-h] [-t] [-v] [-y] [-p] [-Q] [-P] [-Y] [-m step]
        [-r cylinder] [-b blksize] [-l volser] [-d layout]
        [-L] [-V] [-F] [-k] [-C] [-M mode] [-f device] [device]

🦋 DESCRIPTION 🦋

So dasdfmt formats one or several DASD (ECKD) disk drive(s) to prepare them for usage with Linux for S/390. The device is the node of the device, like '/dev/dasda'. Any device node created by udev for kernel 2.6 can be used, e.g. '/dev/dasd/0.0.b100/disc'. It is possible to specify up to 512 devices. 👑

⚠️ WARNING: Careless usage of dasdfmt can result in LOSS OF DATA. Not a vibe, bestie — please read the flags. 😭💀

💅 OPTIONS 💅

  • -h, --help — Print usage and exit. Bye bestie 👋✨
  • -t, --test — Disables any modification of the disk drive. dasdfmt just prints out what it would do. Test mode ate, no cap 🧪
  • -v — Increases verbosity. More yapping, more info 🗣️
  • -f device, --device=device — Specify device to format. For backwards compability only. Old-school but iconic 🎀
  • -y — Start formatting without further user-confirmation. It’s giving “just do it” energy ⚡
  • --norecordzero — Remove permission for subsystem to format write record zero. This is an expert option: Per default in recent dasd drivers, subsystems are granted the permission to format write record zero. This option is used to remove this permission. Expert mode unlocked 🔥
  • -L, --no_label — Omit the writing of a disk label after formatting. This makes only sense for the 'ldl' disk layout. The '-L' option has to be specified after the '-d ldl' option.

e.g. dasdfmt -d ldl -L /dev/...

Order matters, bestie — don’t do it backwards 🙈

  • -V, --version — Print version number and exit. Little version check, slay 🎀
  • -F, --force — Formats the device without performing sanity checking. Highkey dangerous energy, handle with care 😭
  • -C, --check_host_count — Force dasdfmt to check the host access open count to ensure the device is not online on another operating system instance. Safety vibe check ✅
  • -d layout, --disk_layout=layout — Formats the device with compatible disk layout or linux disk layout. layout is either cdl for the compatible disk layout (default) or ldl for the linux disk layout. Compatible disk layout means a special handling of the first two tracks of the volume. This enables other S/390 or zSeries operating systems to access this device (e.g. for backup purposes). Layout lore, iykyk 🦋
  • -p, --progressbar — Print a progress bar while formatting. Do not use this option if you are using a 3270 console, running in background or redirecting the output to a file. Progress bar girlies, know your limits 💅
  • -Q, --percentage — Print one line for each formatted cylinder showing the number of the cylinder and percentage of formatting process. Intended to be used by higher level interfaces. Number-crunching cutie 📊
  • -m step, --hashmarks=step — Print a hashmark every step cylinders. The value step has to be within range [1,1000], otherwise it will be set to the default, which is 10. You can use this option to see the progress of formatting in case you are not able to use the progress bar option -p, e.g. with a 3270 terminal. The value will be at least as big as the -r or --requestsize value. Hashmark moment ✨
  • -Y, --yast_mode — YaST mode; suppress most output. Quiet luxury 💅
  • -M mode, --mode=mode — Specify the mode to be used to format the device. Valid modes are:
    • full — Format the entire disk with the specified blocksize. (default)
    • quick — Format the first two tracks and write label and partition information. Use this option for DASD ESE volumes to take the benefits of thin provisioning. In this case, a full space release precedes the formatting step. If this space release fails, then the formatting also fails. Specify the --no-discard option to omit the space release. For non-ESE volumes use this option only if you are sure that the target DASD already contains a regular format with the specified blocksize. A blocksize can optionally be specified using -b (--blocksize). Quick but not reckless ⚡
    • expand — Format all unformatted tracks at the end of the target DASD. This mode assumes that tracks at the beginning of the DASD volume have already been correctly formatted, while a consecutive set of tracks at the end are unformatted. You can use this mode to make added space available for Linux use after dynamically increasing the size of a DASD volume. A blocksize can optionally be specified using -b (--blocksize). Growth mindset 🌱
  • --check — Perform a complete format check on a DASD volume. A blocksize can be specified with -b (--blocksize). Inspector era 🔍
  • --no-discard — Omit a full space release when formatting a thin-provisioned DASD ESE volume. Thin-provisioned bestie protection 🫶
  • -r cylindercount, --requestsize=cylindercount — Number of cylinders to be processed in one formatting step. The value must be an integer in the range 1 - 255. Use this parameter to exploit any available PAV devices. The number of cylinders optimally matches the number of associated devices, counting the base device and all alias devices. PAV device slay 🚀
  • -b blksize, --blocksize=blksize — Specify blocksize to be used. blksize must be a positive integer and always be a power of two. The recommended blocksize is 4096 bytes. Power-of-two princess 👑
  • -l volser, --label=volser — Specify the volume serial number or volume identifier to be written to disk after formatting. If no label is specified, a sensible default is used. volser is interpreted as ASCII string and is automatically converted to uppercase and then to EBCDIC.

e.g. -l LNX001 or --label=DASD01

The volser identifies by serial number the volume. A volume serial number is 1 through 6 alphanumeric or one of the following special characters: $, #, @, %. Enclose a serial number that contains special characters in apostrophes. If the number is shorter than six characters, it is padded with trailing blanks.

Do not code a volume serial number as SCRTCH, PRIVAT, or Lnnnnn (L with five numbers); these are used in OS/390 messages to ask the operator to mount a volume. Do not code a volume serial number as MIGRAT, which is used by the OS/390 Hierarchical Storage Manager DFSMShsm for migrated data sets.

NOTE: Try to avoid using special characters in the volume serial. This may cause problems accessing a disk by volser. In case you really have to use special characters, make sure you are using quotes. In addition there is a special handling for the $ sign. Please specify it using \$ if necessary.

e.g. -l 'a@b\$c#' to get A@B$C#

Label etiquette is real, bestie 🎀

  • -P numdisks, --max_parallel=numdisks — Specify the number of disks to be formatted in parallel. numdisks specifies the number of formatting processed, independent on the overall number of disks to be formatted. The maximum value for numdisks is 512. Default is 1. Using this option can decrease overall processing time when formatting several disks. Please note that the I/O throughput will dramatically increase when using this option. Use with care. Parallel processing, but make it careful 😳🔥
  • -k, --keep_volser — Keeps the Volume Serial Number when writing the Volume Label. This is useful if the volume already has a Serial Number that should not be overwritten. Protect the volser, periodt 💖

🌈 SEE ALSO 🌈

fdasd(8) — go give it a look, bestie 🦋

Source/version: s390-tools; date: Apr 2006. Cute little time capsule, mwah 🫶💋✨

📦 where this page comes from