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Diskless Linux boot using ZFS, iSCSI and PXE
- deleted 5mo ago[deleted]
- ggm 5mo agoNFS diskless is the more common approach I've used but this is very cool.
- ahepp 5mo agoWhen I tried root-on-nfs I had a lot of issues. The Redhat and Arch package managers don't seem to like it (presumably a sqlite thing?).
- contingencies 5mo agoYou can download the rootfs, extract it to a ramdisk, and just run in memory. This is fast for everything. Unfortunately, memory just got super expensive. Fortunately, Linux requires ~no memory to do many useful things.
- KaiserPro 5mo agoNFS diskless was easier for me to setup when I was doing it. THe caveat was, you needed readonly root, so that meant freezing the OS, anything that needed changing was either stored in a ram disk (that you need to setup) or a per host nfs area (kinda like overlayfs, but not)
- yjftsjthsd-h 5mo agoWhy would you need a read-only root? Do you mean to share across multiple machines?
- KaiserPro 5mo agoYeah it makes things a bit easier to debug. Originally my system was designed to run on multiple machines at once. If you needed to update the root dir, you chrooted into it and did the (yum) update.
- darig 5mo ago[dead]
- protoman3000 5mo agoPretty cool! You could also boot into an ephemeral minimal initrd that displays a selection menu instead of doing it in iPXE. That would grab the new kernel and initrd from the network and kexecs it without reboot.
- theandrewbailey 5mo ago> You could also boot into an ephemeral minimal initrd Wouldn't that need a local disk?
- wallst07 5mo agoNo. PXE boots routinely load the kernel and initramfs directly into RAM with no local disk involved. The initramfs then mounts the real root FS over the network. Then anaconda or whatover os installer picks up and installs the OS in a PXE install sequence when there is a local disk.
- yjftsjthsd-h 5mo agoNice. I'm extra fond of ZFS backed network root filesystem, because it lets you put an OS on ZFS without needing to deal with ZFS support in that OS. (One of these days I want to try OpenBSD with its root on NFS on ZFS, either from Linux or FreeBSD.) Does anyone have an opinion on iSCSI vs NBD?
- Modified3019 5mo agoI don’t have direct experience, but when I looked into it my takeaway that NBD was unable to reliably deal with network interruptions as well as iscsi. https://forums.gentoo.org/viewtopic.php?p=4895771&sid=f9b7ac7f6321fc4d2629cd01a5608f7c#p4895771 https://forums.gentoo.org/viewtopic.php?p=4895771&sid=f9b7ac... https://github.com/NetworkBlockDevice/nbd/issues/93 https://github.com/NetworkBlockDevice/nbd/issues/93 Whether that’s the case with the latest version, I don’t know, but it’s something you might test if you choose to try it.
- jaypatelani 5mo agoYou might like https://smolbsd.org/ https://smolbsd.org/
- yjftsjthsd-h 5mo agoWell yes, I do like that:), but I don't see the connection to this thread?
- guenthert 5mo agoWell, iSCSI is a standard, so chances are better that it's supported in a non-Linux OS, e.g. MS Windows. Years ago I booted a Windows (7, iirc) client that way, but gave up on it (too much hassle and performance limited by the network) when SSDs became cheap.
- nubinetwork 5mo agoI think you need NBD if you're going to use glustre, but I could also be thinking of ceph.
- rwmj 5mo ago
- ahepp 5mo agoYou might find it worth upgrading to 10gbps if you continue to go down this road. The Mikrotik CRS-309 has served me well, and a couple Intel X520-DA2s. I believe those NICs can do iSCSI natively, and pass the session to the operating system with iBFT. SFP28 might be cheap enough now too, I'm not sure...
- dhash 5mo agosomething worth mentioning here is that iSCSI is quite unhappy on congested networks or packet loss caused by incast traffic. to make this actually work well, consider modifying your switches QoS settings to carve out a priority VLAN for iSCSI traffic
- fragmede 5mo agoor a north-south/east-west architecture, so there's an entirely separate network just for iSCSI. Control plane vs data plane.
- tehlike 5mo agoI used similar ipxe setup for robotic cluster - every robot booted from the same thing, then kubernetes managed the containe orchestration. it was fun.
- anonymousiam 5mo agoI've done a lot of headless/diskless stuff. I haven't done much for years, because my NAS only has gigabit Ethernet ports. I can cascade them and get four Gbps downstream, but it's still painful. I have recently upgraded my house to 10Gbps Ethernet, with only one room still stuck at gigabit, and unfortunately, it's my main office. I'm working on getting the drop there now (literally, just taking a break here). Even once I'm done, accessing an iSCSI drive over 10GbE will be 4-8 times slower than a local NVMe drive, but it will sure be a lot better than it was! Ideally, I could run VMs on the NAS and have great performance, but that's another hardware upgrade...
- ReDress 5mo agoReally I wonder how this turns out to be diskless while you're clearly accessing a disk/drive over the network. Shouldn't we refer to this as network boot?
- pdpi 5mo agoIt's diskless from the point of view of the device being booted.
- olavgg 5mo agoUsing a proper NIC (Chelsio) with their iSCSI accelerator will boost your iSCSI performance significantly. Another alternative is Mellanox with RDMA. You need CX4+ for optimal performance over TCP/IP, while the cheap CX3 is excellent with IPoIB. If you have a lot of packet drops and retransmissions, another option for boosting iSCSI performance is getting a network switch with a lot of memory for packet buffering. This helps with incast congestion. There are special switches with gigabytes of memory built for this. NVMe-oF is the best protocol with least overhead for network drives, with a proper setup you lose only 10-20% latency compared to local disk even with Intel Optane. Throughput should be almost similar.
- RulerOf 5mo ago> Another alternative is Mellanox with RDMA. You need CX4+ for optimal performance over TCP/IP, while the cheap CX3 is excellent with IPoIB. Do these benefit the iSCSI target end of the equation too, or just the initiator? And do they work like an HBA, where you configure the card in a firmware setup menu, or does it just transparently accelerate the software initiator on Windows/Linux?
- louwrentius 5mo agoI would probably recommend to look into NVMe over TCP over iSCSI, especially for fast NVMe drives.
- deathanatos 5mo ago> UEFI fixes that to some extent, but it’s a pain to maintain the UEFI entries manually and change them every time the kernel updates. … you don't have to update the UEFI entries every time the kernel updates. (I guess you might if you do like a kernel w/ CONFIG_EFI_STUB, and you place the new kernel under a different filename than what the UEFI boot entry point to then you might … but I was under the impression that that'd be kind of an unusual setup, and I thought most of us booting w/ EFI were doing so with Grub.)
- yjftsjthsd-h 5mo agoEven if you do CONFIG_EFI_STUB, there should be a post-update hook to automatically call efibootmgr.
- nicman23 5mo agoor just copy the latest kernel to something like /vmlinux and /initramfs
- creshal 5mo agoOr use UKI and throw the current kernel to /efi/boot/bootx64.efi; there's plenty of solutions to sane bootloader/kernel management if you're willing to invest 15 minutes into the topic and not act like it's scary and complicated (it really is the opposite).
- nicman23 5mo agowhat i want to play with is rdma and having a bcache block device with the remote as a backing and a small local nvme as a write-through cache
- Tepix 5mo agoThis could be an interesting setup for booting off a NAS like Synology or QNAP. I haven't really used iSCSI, it's intimidating how much prep this takes...
- burner420042 5mo agoThe 'target' moves slow so once you learn it, it all stays relevant forever. ... And it's very, very fun.
- Tepix 5mo agoDoes it offer performance advantages over NFS root?
- a96 5mo agoI kind of expect the performance is worse, but one neat thing is that iscsi is a block device, so you could run e.g. disk crypto, volume management or whatever on it. Not to mention any FS. And you don't need to deal with NFS or RPC.
- bobmcnamara 5mo agoDunno about performance vs NFS, but I've stuffed an unaware OS onto ZVOL-over-iSCSI using a NIC with option ROM.
- burner420042 5mo agoThey operate at different layers. iscsi is a block device: you gain a 'disk drive' sitting on your network. A dedicated network for disk traffic and use it to host on-prem virtualization. It's called a SAN array.
- Tepix 5mo agoSure, but eventually you will reach a layer with files, usually. Then you can run benchmarks and compare numbers.
- 5mo ago
- guenthert 5mo ago"I didn’t want to get into the hassle of repartitioning everything that the boot loader works with both Linux & Windows." Hmmh? I haven't done so in years, but configuring multi-boot used to be considerably easier than disk-less operation.
- pbhjpbhj 5mo agoSecureBoot is a PITA.
- jeroenhd 5mo agoFor Debian and most other distros, secure boot isn't a problem. Installers are all using a signed, trusted-by-default bootloader. There are some exceptions (some hardware from Microsoft doesn't trust the third party certificate used, for instance, and Red Hat Enterprise has their own root of trust if you opt into that), but they're very rarely ever an issue.
- jeroenhd 5mo agoThe Debian installer is less than optimal for repartitioning. The Linux NTFS resizing code also has a tendency to trigger data corruption. Not really Linux' fault, but it's a good reason to do partitioning from inside of Windows, which can be a pain already. Another issue I've run into is Windows creating a very small (~300MiB) EFI partition that barely fits the Windows bootloader, let alone a Linux bootloader and kernel. You can resize and recreate the partition of course, but reconfiguring Windows to use a different boot partition is a special kind of hell I try to avoid.
- charcircuit 5mo ago>Not really Linux' fault If Linux corrupts someone files, it is 100% Linux's fault and is absolutely unacceptable.
- snailmailman 5mo agoIt is relatively easy to configure. Just install Linux after windows, and Linux will generally automatically setup a boot-selection screen for you. The installer should detect windows and even shrink the partitions for you. You can install a prettier looking boot selection menu like rEFInd, but the default works just as well, and I think the mainstream distros all setup secure boot too. On my pc it was very easy, on my (8yr old) laptop I had to add some secure boot keys and the bios was very confusing, using terms that didn’t seem to match what they should have been. My setup has worked almost entirely flawlessly and survived updates from both OSes. Only issue being “larger” windows feature updates putting windows back as the first OS in the list, but that happens maybe once or twice a year? And it’s a quick bios change to fix the order.
- verytrivial 5mo agoI know it was just a convenient pretext for a learning journey, but do not come away from this thinking llama.cpp needs to be compiled on Windows before use. The GitHib project has a cornucopia of pre-built artifacts to use. https://github.com/ggml-org/llama.cpp/releases https://github.com/ggml-org/llama.cpp/releases
- shevy-java 5mo agoI have to admit, I misread "Diskless Linux" initially ...
- iberator 5mo agoDoes zfs support error correcting instead of just finding (already) broken files? I have been waiting for such a feature for like 15 years now. Without it, zfs is just a fad and useless filesystem (all that complexity for NOTHING). ext2 for the win! still
- tecleandor 5mo agoI don't know if I'm understanding your question, but ZFS actively corrects data on disk when it finds a checksum error [0]. Those checksum errors can be found when accessing that data, or doing a 'scrub' action that scans the whole volume to check integrity. -- 0: https://klarasystems.com/articles/troubleshooting-zfs-common-issues-how-to-fix-them/
- olavgg 5mo agoZFS supports self healing, you do not have scrub, it will be corrected during a bad read as long you have a copy. Metadata has 2 copies by default for additional safety for a single disk.
- a96 5mo agoVery neat. I've never seen the Debian installer using iscsi. No other installer either for that matter. Looks like ZFS is only used to store the image on the server, though. I was expecting this to be more interesting because of that.
- cwillu 5mo agoFriends don't let friends use grub. rEFInd is _so_ much simpler: one efi entry, one text config file in the efi partition, nothing that needs to change when the kernel updates, and no massive pile of templating and moving parts to mysteriously break dumping you at an impenetrable grub “rescue” shell.
- DaSHacka 5mo agoThere's also systemd-boot, which seems to be getting more popular. https://systemd.io/BOOT/ https://systemd.io/BOOT/
- cogman10 5mo agoThat's what I'm currently using in gentoo and it's fine. Realistically there's only 1 config file to modify if I want to change kernel settings and otherwise it just works. That said, I'm probably going to try a straight EFI boot on my next laptop. https://wiki.gentoo.org/wiki/EFI_stub https://wiki.gentoo.org/wiki/EFI_stub
- mdhen 5mo agoSystemd-boot is my choice for any simple boot scenario. Love it. Agreed that grub is a mess
- ChocolateGod 5mo agoOr just use systemd-boot which uses BLS thus there are no config files.
- ux266478 5mo agoBLS means many config files instead of one, not zero config files.
- NekkoDroid 5mo ago> BLS means many config files instead of one Which ones? If you want to all you need is a single UKI in /EFI/Linux and everything is synthesized from that.
- qzgrid37 5mo ago[dead]
- MohammadAbuG 5mo agoThis man is diskless
- lproven 5mo agoI like the concept, I don't like the presentation or the reasoning. But this idea or ones much like it have been presented before... "Hassle-free diskless Virtual Machines with Xen and Alpine Linux" https://jonnytyers.wordpress.com/2016/08/16/hassle-free-diskless-virtual-machines-with-xen-and-alpine-linux/ https://jonnytyers.wordpress.com/2016/08/16/hassle-free-disk... "How to make a Diskless Virtual Machine (KVM)" https://github.com/lispydev/diskless-kvm https://github.com/lispydev/diskless-kvm And if you just want a dead easy PXE server for bare metal... https://www.iventoy.com/en/index.html https://www.iventoy.com/en/index.html
- ersoft 5mo agoiSCSI is great and underated, I've been running iSCSI volumes for OrangePI boards which had only SD card support for years. Performance was much better on Gigabit Ethernet vs the SD card.
- spacecow 5mo agoHeartwarming to see iSCSI still in use! I originally made this account while certifying devices against good ol' RFC 3720 at an interop lab quite a long time ago now...
- throw0101c 5mo agoStill miss the Open Firmware (IEEE 1275) "boot net" from my Sun Solaris days (and PowerPC Macs). * https://en.wikipedia.org/wiki/Open_Firmware https://en.wikipedia.org/wiki/Open_Firmware
- MisterTea 5mo ago> apt install apache2 git ansible tftpd-hpa targetcli-fb Ansible? Amazing amount of complexity for something so simple. Sigh ... Linux. It's just a commercial toaster to me these days. I net boot 9front and it takes 5 minutes to setup. Plus it's all built in so you don't need to install anything. Just enable tfp and dhcp on the 9 machine (no issue for me since 9 runs my network) then setup a few lines in your ndb file for the machine you want to boot which includes Mac, IP and boot image file. Then you need a simple plan9.ini and boot scripts for the machine in /cfg/. Last, a quick change to the root file server to listen on IP Then power on the machine and it boots from the same root fs so your starting at your desktop on a new machine. Done. Why make something so awesome so difficult?
- yjftsjthsd-h 5mo ago> no issue for me since 9 runs my network That's more interesting than the netboot thing. Is 9front running your router? What do you do for WiFi? Have you written this up, and/or could you point me to any references for doing it?
- MisterTea 5mo agoThis is what I followed: https://posixcafe.org/blogs/2024/01/04/0/ https://posixcafe.org/blogs/2024/01/04/0/ However, at the moment my network is in shambles so I'm only running 9front for dhcp/dns/tftp. Lots of life things so I haven't had time to properly setup everything. Wi-Fi is handled through a freebie unifi AP friend gave me. I run the controller in a docker manually when needed.
- stereo-highway 5mo agoThis post generated more attention than I expected. I wanted to share something that i got working at home on consumer hardware and with software that I’m slightly more familiar with. This is by no means the only way to implement this, an I’m sure there are better ways. Thank you for the feedback, I’ll edit it and add more points on alternative stacks and the iSCSI network pickiness.
- virusduck 5mo agoIt's true. This boot has no disk
- aidenn0 5mo agoYour comment makes me hope that the hostname of the machine is walter-peck.
- 1vuio0pswjnm7 5mo agohttps://web.archive.org/web/20260507031624if_/https://aniket.foo/posts/20260505-netboot/ https://web.archive.org/web/20260507031624if_/https://aniket...
- arrrrr 5mo agoWe did something similar with Ubuntu LTSP 10 years ago. Had tens of diskless office computers as fat clients booting from a single server and running everything in ram. Update? Just rebuild the base image and reboot the stations. Way better than any windows setups for offices, where you need many identical stations.
- sovenyr 5mo ago[dead]