CONFIG_BLK_DEV_UBD_SYNC: Always do synchronous disk IO for UBD

General informations

The Linux kernel configuration item CONFIG_BLK_DEV_UBD_SYNC has multiple definitions:

Always do synchronous disk IO for UBD found in drivers/block/Kconfig

The configuration item CONFIG_BLK_DEV_UBD_SYNC:

• prompt: Always do synchronous disk IO for UBD
• type: bool
• depends on: CONFIG_BLK_DEV_UBD
• defined in drivers/block/Kconfig
• found in Linux kernels: 2.6.11–2.6.39, 3.0–3.19, 4.0–4.20, 5.0–5.19, 6.0–6.12, 6.13-rc+HEAD

Help text

Writes to the virtual block device are not immediately written to the host's disk; this may cause problems if, for example, the User-Mode Linux 'Virtual Machine' uses a journalling filesystem and the host computer crashes.

Synchronous operation (i.e. always writing data to the host's disk immediately) is configurable on a per-UBD basis by using a special kernel command line option. Alternatively, you can say Y here to turn on synchronous operation by default for all block devices.

If you're running a journalling file system (like xfs, for example) in your virtual machine, you will want to say Y here. If you care for the safety of the data in your virtual machine, Y is a wise choice too. In all other cases (for example, if you're just playing around with User-Mode Linux) you can choose N.

Always do synchronous disk IO for UBD found in arch/um/Kconfig_block

The configuration item CONFIG_BLK_DEV_UBD_SYNC:

• prompt: Always do synchronous disk IO for UBD
• type: bool
• depends on: CONFIG_BLK_DEV_UBD
• defined in arch/um/Kconfig_block
• found in Linux kernels: 2.5.45–2.5.75, 2.6.0–2.6.10

Help text

Writes to the virtual block device are not immediately written to the host's disk; this may cause problems if, for example, the User-Mode Linux 'Virtual Machine' uses a journalling filesystem and the host computer crashes.

Synchronous operation (i.e. always writing data to the host's disk immediately) is configurable on a per-UBD basis by using a special kernel command line option. Alternatively, you can say Y here to turn on synchronous operation by default for all block devices.

If you're running a journalling file system (like reiserfs, for example) in your virtual machine, you will want to say Y here. If you care for the safety of the data in your virtual machine, Y is a wise choice too. In all other cases (for example, if you're just playing around with User-Mode Linux) you can choose N.

Hardware

LKDDb

Raw data from LKDDb:

• (none)

Sources

This page is automaticly generated with free (libre, open) software lkddb(see lkddb-sources).

The data is retrived from:

• Linux kernel
• Linux Kernel Driver DataBase (LKDDb)

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