from Hacker News

Show HN: go-nbd – A Pure Go NBD Server and Client

by pojntfx on 3/29/23, 4:23 PM with 44 comments

Hey HN! I just released go-nbd, a lightweight Go library for effortlessly creating NBD servers and clients. Its a neat tool for creating custom Linux block devices with arbitrary backends, such as a file, byte slice or what I'm planning to use it for, a tape drive. While there are a few partially abandoned projects like this out there already, this library tries to be as maintainable as possible by only implementing the most recent handshake revision and baseline functionality for both the client and the server, while still having enough support to be useful.

I'd love to get your feedback :)

by davidjfelix on 3/29/23, 5:30 PM
NBD = network block device. Hope I saved somebody a google.
by rkeene2 on 3/29/23, 8:26 PM
NBD is a simple protocol, I used it to recover a RAID5 hardware array that lost parity [0] [1], in just a few lines of C.
[0] https://dev.to/rkeene/raid5-lost-raid5-recovered-3kld
[1] https://www.rkeene.org/projects/info/resources/diatribes/blo...
by cellularmitosis on 3/29/23, 6:50 PM
Very cool! I'm curious if you've explored testing error cases yet? Years ago I fooled around with nbdkit and developed a "bad sectors" and "bad disk" plugin and found that the error handling around these scenarios left a little to be desired.
https://github.com/pepaslabs/nbdkit-baddisk-plugin
https://github.com/pepaslabs/nbdkit-badsector-plugin
by Thaxll on 3/29/23, 6:12 PM
You should probably defer mutex unlock() and not use naked returns: https://github.com/pojntfx/go-nbd/blob/main/pkg/backend/file...
Defering overhead is very small nowdays.
by latchkey on 3/29/23, 5:52 PM
Since this heavily involves networking, take a look into using gnet [0]. You might find some interesting performance improvements by using that over just net.Conn.
[0] https://github.com/panjf2000/gnet
by coppsilgold on 3/29/23, 11:57 PM
I use NBD for my single-user NAS. You can use FDE (full disk encryption, luks) client-side.
The system managing the physical block devices never sees unencrypted data.
Such a setup shines when you use a laptop as your main machine and wish to have a lot of secure storage. The approach I chose was to bond ethernet & wifi6e, use wireguard (w/ PSK). And wonder the house with uninterrupted access.
by rvalles on 3/30/23, 5:10 AM
NBD is fairly simple. I wrote a minimal server in Python[0]. It is just a few lines.
0. https://github.com/rvalles/pyamigadebug/blob/master/NBDServe...
by lenkite on 3/30/23, 6:56 AM
I misread this as NZB for usenet and was excited someone had written one in Go.
by i5heu on 3/29/23, 6:04 PM
NBD = https://de.wikipedia.org/wiki/Network_Block_Device