ublkpp

Intro

A target for Linux' userspace block driver, currently based on ublksrv IO_URING implementation.

QuickStart

Build Library

$ git clone git@github.com:szmyd/ublkpp
$ ublkpp/prepare_v2.sh
$ conan build -s:h build_type=Debug --build missing ublkpp

Example App

An ublkpp_disk application can be used to try out basic RAID1/0/10 capabilities with a single Target. The lifetime of the ublk device is tied to the lifetime of the process itself.

Build and Run Example Application

$ conan build -s:h build_type=Release --build missing ublkpp
$ sudo modprobe ublk_drv
$ fallocate -l 2G file1.dat
$ fallocate -l 2G file2.dat
$ fallocate -l 2G file3.dat
$ fallocate -l 2G file4.dat
$ hexdump -n 256 file*.dat
    0000000 0000 0000 0000 0000 0000 0000 0000 0000
    *
    0000100
$ sudo ublkpp/build/Release/example/ublkpp_disk -scv 2 --raid10 file1.dat,file2.dat,file3.dat,file4.dat
    ... // SuperBlock Initialization
    [07/06/25 18:01:50] [info] [build/Release/example/ublkpp_disk] [223787] [ublkpp_tgt.cpp:178:start] Device exposed as UBD device: [/dev/ublkb0]

Usage

In another session we should find the exposed BLOCK device.

$ lsblk
    NAME        MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
    ...
    ublkb0      259:3    0    4G  0 disk

Write Data into ublk Device

$ sudo dd if=/dev/urandom of=/dev/ublkb0 bs=4k count=1 
    1+0 records in
    1+0 records out
    4096 bytes copied, 0.00407932 s, 126 kB/s
$ hexdump -n 256 file1.dat
    0000000 2553 0aff 9934 c53e 3a67 17c8 ae49 641b
    0000010 0100 a0d8 b2c5 e056 7144 61af 0854 461f
    0000020 4c0f 0001 0000 0000 0000 0000 0080 0001
    0000030 0000 0001 0000 0000 0000 0000 0000 0000
    0000040 0000 0000 0000 0000 0000 0000 0000 0000
    *
    0000100

If we dump the first 4KiB of any backing device we'll find the RAID-1 SuperBlock for the first Stripe.

License Information

Primary Author: Brian Szmyd

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at https://www.apache.org/licenses/LICENSE-2.0.

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITHomeStore OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.