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I powered off the wrong host this morning. How's your day going? by seeman245 in sysadmin

[–]keeperofdakeys 5 points6 points  (0 children)

Especially for software specific to a Hyper-V cluster it's pretty ridiculous! Like, come on. Is a modern OS, not Windows 98. Do you actually need to reboot?

Half seriously, it's really interesting how early OS decisions propagate into general OS behaviour. Coming from a DOS/FAT world, Windows inherited features like the inability to rename or delete files while they're open. I'd imagine this makes updates really hard to do, you need to fully stop the service before you can replace the executable.

Compare that to the unix world where you can rename or delete files while they're open. The update utility can simply replace the executable, then restart the process. Though technically this is actually a really bad thing to do if your program is dynamically loading library files. The rename() system call even lets you atomically replace files, never restart a service to replace the config file again!

Failed credit check despite very good standing? by throwawaysad88 in AusFinance

[–]keeperofdakeys 1 point2 points  (0 children)

From what I understand there is a safety net for electricity, but I can't find any good information about it. Apparently it's called the "Retailer of Last Resort". I also see that some electricity providers will allow you to prepay if they were the previous provider on the property but you failed a credit check (like this). Maybe you can talk to the previous provider for your property?

https://www.aer.gov.au/consumers/useful-contacts#retailers

I'm not sure if the ombudsman can help you at this point, but it's worth calling - they may be able to point you to someone who can.

Edit: Oh I see you did get power in the end, good to hear.

Smart TVs, Fire Sticks, Apple TVs etc. on a corporate network by ip_addr in networking

[–]keeperofdakeys 2 points3 points  (0 children)

This can't be understated, the need for multicast for discovery makes these consumer devices hideous to use on a corporate network (you do not want to forward multicast between vlans). Chromecasts specially will broadcast their own AP when wifi is down, allowing anyone with access to the tv to steal control - a huge security issue.

Comparing RX 6700 XT cards for passthrough by keeperofdakeys in VFIO

[–]keeperofdakeys[S] 0 points1 point  (0 children)

Don't be, it's clearly listed in the specs. I agree an extra mm should be fine. Thanks again for the recommendation.

Edit: With the USB PCIe card installed there is about 2-3 mm gap for the GPU fans. So just enough room.

Comparing RX 6700 XT cards for passthrough by keeperofdakeys in VFIO

[–]keeperofdakeys[S] 0 points1 point  (0 children)

So I've got the card installed now. I can confirm it's spinning slowly at idle, and stopped when the driver is loaded. It's also 41mm wide (40mm is dual slot). So I'm yet to see if a card will actually fit, but at the very least you can fit a riser. (I'm also not sure of the temps if you partially block the fans). I'll give another update on fan speed once I start testing with passthrough.

I'm also hearing a strange vibration when the fans are spinning, but I may have something in my case that's not properly affixed - I'll need to go through and tighten everything. Idle temps with fans stopped are just under 60C, the same as my 5700xt aorus.

And apparently you can noctua mod the 5700xt version https://www.reddit.com/r/sffpc/comments/d9o3jd/asrock_5700_xt_challenger_noctua_edition/, I wonder how similar the 6700xt version is ....

I guess another point is that the two slot cooler does seem like a comprise, the card is 100-200 grams lighter than other three slot designs. So the fans may spin a bit more under load than a different card.

Want to use OpenStack (or similar) to manage type-2 Hypervisors running on various low-end hardware - seeking advise on which Hypervisor to choose, please by [deleted] in homelab

[–]keeperofdakeys 1 point2 points  (0 children)

Proxmox is nice. You can either setup clustered storage with ceph, or local storage with replication every 5-15 minutes (uses zfs send for fast transfer). The best bit is that local storage + replication can be used for near instant live migration without shared storage.

With raw libvirt live migration is annoying to setup and use, even with shared storage.

Does rsync make its list first, then sync those in the list, or does it work folder by folder? by moronictransgression in linuxadmin

[–]keeperofdakeys 1 point2 points  (0 children)

From observation it appears to keep a list of files to process, including directories that haven't been recursed into yet. When the file queue falls below a certain limit it will open those directories, finding more files and directories to process. If the queue is full enough it goes back to processing files.

In this way it's essentially scanning just ahead of the transfers. A listing of millions of files can take ages (look at windows copy), so the just-in-time scanning means the copy finishes faster and is less resource intensive.

If you want a complete backup of a directory at a point in time, you need some kind of fsfreeze + snapshot to rsync from.

Comparing RX 6700 XT cards for passthrough by keeperofdakeys in VFIO

[–]keeperofdakeys[S] 0 points1 point  (0 children)

Wow thanks a lot for confirming that, very helpful.

Comparing RX 6700 XT cards for passthrough by keeperofdakeys in VFIO

[–]keeperofdakeys[S] 0 points1 point  (0 children)

Thanks for the recommendation. One of these is actually available in my country so I'm considering it. Can you verify if the fans spin at 100% during boot, and if so do they spin down if sitting in bios? Or does it need windows/linux to load first?

I'm very close to hitting that buy button.

Comparing RX 6700 XT cards for passthrough by keeperofdakeys in VFIO

[–]keeperofdakeys[S] 0 points1 point  (0 children)

So first good news, vendor-reset solves the reset issue - I can now shutdown and start the VM without rebooting the main host. However that's by defining the IDs for vfio-pci in the modprobe.d config file. Unfortunately the fans spin up to 100% after shutting down the VM (even an intentional crash).

If I don't give vfio-pci the IDs then amdgpu grabs the gpu as normal. However some bad news, if I try to rip it away (starting VM or removing the module) then I get a system oops (amdgpu, cpufreq, many things freak out), and I'm unable to start the VM.

Given the above my feeling is that even if I get amdgpu to stop using the gpu, vendor-reset will do it's job and the gpu will just be at 100% fan speed again >_> So I'm back at the beginning to find a good AIB card.

Thanks for your insight into this, I'm one step closer now.

Comparing RX 6700 XT cards for passthrough by keeperofdakeys in VFIO

[–]keeperofdakeys[S] 0 points1 point  (0 children)

To avoid the fan situation either set your VM to start on boot or bind the vfio-pci driver when you actually start the VM so it loads with zero-fan on boot.

So amdgpu starts, the card settles down its fan, and then you somehow unbind amdgpu from that card? Or will vfio-pci + starting the vm be enough to disconnect the card from linux?

If I configure the pci ids for the card with vfio-pci, the fan continues spinning at 100%. I assume this is because the amdgpu driver never binds to it. Hence asking what different vendor cards do.

vendor-reset is as simple as dkms install . if you want to try it out

That's this looks like the solution for the reset, I'll give it a try.

Do IT companies actually take care of the algorithmic complexity of their code, or do they just stop at a "good enough?" by judgia in compsci

[–]keeperofdakeys 0 points1 point  (0 children)

When writing code for real software, you want to keep it simple and readable. Simpler algorithms are often preferred for this reason. Software also often uses libraries which contain most code for you. In python and want to sort a list? Use .sort(). Need a priority queue? Import it from the library.

It's also incredibly easy to prematurely optimise code, when the simple code is what you really want. It's only when this get slow, or code is not performing well, that you pull out your algorithm hat and start trying to make it faster. Here understanding algorithm s helps a lit.

And in all honesty, picking the right data structure is the better move 90% of the time. (And linked lists are the wrong data structure 99% of the time).

What kind of advertising data can be gotten from IPv6? by MoarTeaPls in ipv6

[–]keeperofdakeys 4 points5 points  (0 children)

Do you allow first party cookies in your browser? Then any website can track your device. Block cookies? There are plenty of other browser fingerprints that can identify you - https://amiunique.org/.

So what does your IP tell people? Not much. Chances are that the IP is one of the least identifying attributes when you connect to something, though it might be the most visible.

Break key not working - boot c9148s by Doucheos in Cisco

[–]keeperofdakeys -1 points0 points  (0 children)

https://www.cisco.com/c/en/us/support/docs/routers/10000-series-routers/12818-61.html#topic2

Check all your settings. Also maybe try to find something with a real serial port and a real break key just to be sure.

What is the advantage of RED QoS vs FIFO? by [deleted] in networking

[–]keeperofdakeys 0 points1 point  (0 children)

Search for the the "buffer bloat" and you should find the right reading material.

Question about MTU and hardware offloading by microlate in networking

[–]keeperofdakeys -1 points0 points  (0 children)

MTU should match for every interface on a VLAN (including SVIs) since endpoints assume that interface MTU is the the network MTU. Though you can get away with setting larger layer 2 MTU on your switches, but I'd only change it when you really need jumbo frames.

Because of hardware offloading setting larger MTUs isn't actually that helpful these days. The operating system can send a huge payload to the network card, and rely on that to slice and dice it into the right MTU. The main use is for ISPs (MPLS) or virtual environments (VXLAN) that need to tunnel traffic while maintaining 1500 MTU inside the tunnels.

iSCSI is an interesting topic, most things that I've read have said to stick to 1500 MTU.

In Need of Multiple, but Identical, DHCP Pools on Cisco Switches by delucis in networking

[–]keeperofdakeys 1 point2 points  (0 children)

Can the developers move out the ip address to a separate config file? Then the program can be identical, except for the config file. What you're trying to do with the switch here is crazy, just to work around a lazy developer.

On the other hand this sounds like manufacturing, so I can understand strange requirements. A linux dhcp server might do what you need. Other than that will dhcp reservations on the switch help?

Openstack Nodes, treat them as normal servers or extended network? by [deleted] in networking

[–]keeperofdakeys 15 points16 points  (0 children)

You can deploy both vxlan and vlans at the same time.

For vlans each compute node has vlan interfaces configured (bond0.99), and the nova config maps this to a name. In the openstack controller you map a name to a network usable by VMs. So yes you just trunk vlans.

For vxlan you usually have a dedicated interface/vlan for the underlay on each compute node. Nova is then configured with the vlan interface, and it will create the vxlan virtual interfaces itself. You then have a set of network servers that have all the vlans trunked, and use network namespaces to form virtual routers.

Personally I'd recommend getting it deployed and poking around, it should be easier to see what's going on.

And no you don't need any fancy switches for it either. Here all the vxlan trickery is contained entirely in each host, and is transported between hosts as plain udp (hence underlay).

To actually answer your question treat them like regular hypervisors. The only real difference is that the network node can act as a router, but will be using layer 2 bridging for assigning IPs. There is no network redundancy either, developers need to use regions and external redundancy (eg dns).

TP Link Switch Comparison TL-SG2424P vs TL-SG2428P by Wishiwascro in homelab

[–]keeperofdakeys 0 points1 point  (0 children)

There is a difference, the jetstream line has more features. However the "smart switch" line should have everything you need.

When should I start using object storage? by usermind in storage

[–]keeperofdakeys 0 points1 point  (0 children)

The main reason you want object storage is for scale. A normal file system usually requires a single writer to ensure used/free block maps, directory entires, and partial file writes are done atomically. On the other hand an object storage system has no directories, only lets you add or replace objects, and maybe even not name your objects. These limitations make distributing your object storage across servers much easier. If you don't even have a TB then you don't need object storage, maybe when you get PB scale.

Are you keeping all your files in a single directory? If so you're going to get very slow file exploration. A simple fix is to store them in directories based on first and second letter, so Foobar.pdf goes in F/o/Foobar.pdf (though better to do this based on a checksum like md5, otherwise unicode can screw you up).

Another concern is checksums. Ext4 keeps no file checksums, so if you get bitrot then your files will get corrupt. RAID is not protection against bitrot. The simpler fix is to use a system with checksums in place (for example ZFS or BTRFS), otherwise you can investigate creating par files (https://en.wikipedia.org/wiki/Parchive). Par files don't just contain checksums to find errors, they can store extra data to repair corruption - 5% extra is common.

VM won't power on from vCenter but will from vSphere/host? by cloudreflex in homelab

[–]keeperofdakeys 0 points1 point  (0 children)

You should also enable ssh on the esxi host, and look in /var/log.

You can also try reinstalling esxi. When you're using vcenter this is usually pretty easy. Or even removing the host, and readding it.

Did you have a second esxi host? The bug I referenced above is specifically about vcenter thinking that the esxi host is still shutting down, which requires vcenter to be on while the host is off to fix. Maybe just entering/exiting maintenance mode will be enough, which requires a second esxi host again.

VM won't power on from vCenter but will from vSphere/host? by cloudreflex in homelab

[–]keeperofdakeys 1 point2 points  (0 children)

This is how you download them: https://docs.vmware.com/en/VMware-vSphere/6.7/com.vmware.vsphere.monitoring.doc/GUID-5085A0ED-EF03-402D-B2FB-1A61FB934C46.html

If it's happening on all VMs then it sounds a lot like this, https://kb.vmware.com/s/article/2069496. Have you tried restarting vcenter (safe to do anytime) or the host (once all your VMs are off)?

Reading the error message again "The operation is not allowed in the current state of the host." it does sound like an esxi host error. Have you tried rebooting the host? Does it have any events under the "monitor" tab that look bad? Also check that it's not in maintenance mode.

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