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ruben23hi guys anyone can help how to add user or user email on my postfix mail server, anyone have idea.?04:32
lordievaderGood morning08:30
=== denningsrogue6 is now known as denningsrogue
vlmi made a raid 1 from two raid 0 arrays with mdadm,how do i go about scrubbing the raid,is it enough to scrub the main raid 1?15:56
sdezielvlm: did you kind of re-implemented raid10 by stacking multiple md devices?16:00
vlmsdeziel: dunno maybe,ive never made a raid before though,thought this was how i could make a raid 10 or could i do it right away?16:28
sdezielvlm: I got confused what you built is called a raid0+1. It seems that mdadm requires stacking like you did for this raid level. raid10 is similar (but inverted) and has native support by mdadm, no stacking required16:29
vlmsdeziel ah ok ,ill head over to kernel.org try get read the guide there and read up on lvls aswell thanks for asnwer16:30
sdezielvlm: you should probably take a look at ZFS too. I've switched away from mdadm to ZFS and wouldn't look back16:31
sdezielthere are some special edge cases where mdadm is a better solution but for pretty much everything else, I feel ZFS nails it16:32
vlmsdeziel yeah i always wanted to give it ago,just i keep reading here and there that is not as stable or so as it is in freebsd and such?16:32
sdezielvlm: I seriously question those claims. ZFS is in 'main' on Ubuntu, so you get good support for it. Been working well since 16.04 IIRC16:33
vlmsdeziel also i think with raidz i wanted i couldnt easily expand it without requiring much more hardware or so i think it got expensive16:33
vlmsdeziel oh thats nice to hear though,yeah i always wanted a raidz or so16:34
sdezieltrue, growing a zpool requires some thinking. That's why usually go with simple mirroring that are all tied up into a stripe at the zpool level16:34
sdezielthis gets you a kind of raid10 on steroid that is easy to grow16:35
vlmsdeziel ill look into that,though this is just a simple raid i dont need snapshots for it so maybe ill be ok with mdadm16:36
sdezielmaybe you don't need snapshot but you surely want checksums to protect your data ;)16:37
sdezieland transparent compression, and ...16:37
vlmsdeziel: though doesnt the mdadm scrubs do that ?16:37
sdezielnot really16:37
sdezielor I should say, really not ;)16:38
sdezielI don't have to go into details ATM but if you care about your data ZFS has more to offer natively than mdadm can do16:38
vlmsdeziel alright think ill consider trying it then if i can achieve the same setup 0+116:40
vlmsdeziel: i now made one vdev i believ consisting of 2 mirrors,that should be the same as 0+1 shouldnt it?17:38
sdezielvlm: that's more akin to raid1017:38
vlmsdeziel: arent thouse in effect the same or so?17:41
vlmsdeziel: they seem so similar to me -_-17:41
sdezielvlm: I'm not an expert by any mean, I'm basically looking at https://en.wikipedia.org/wiki/Nested_RAID_levels17:42
vlmsdeziel: im seeing a noticable improvement in throughput now though,up 200MB/s + up from 184MB/s something17:42
sdezielvlm: but ZFS is a different beast17:42
sdezielvlm: while you benchmark your new array, check 'zpool iostat -v 1'17:44
vlmsdeziel: my initial reading tells me they are the same in performance and redundancy, just different layout also raid 10 might not be supported on ancient hardware maybe17:47
vlmsdeziel: my system is very low on ram so that might get challenging i tuned arc_max and min for starters now i need to read up on how to track down if there a memory issues17:48
sdezielvlm: you can reduce the ARC usage if you really cannot afford the RAM cost... it will harm the performance of course17:50
sdezielyou can tune the ARC usage by tweaking the 'primarycache' setting on any ZFS or ZVOL17:51
vlmsdeziel: just random search on web says about 1G ram on 1TB of storage17:51
sdezielon tightly constrained machines (512M of available RAM), I ran with just metadata caching17:51
vlmsdeziel: what size of pool?17:52
=== ijohnson is now known as ijohnson|lunch
sdeziel vlm: it was a mirror of 2x 750GB18:30
vlmsdeziel: nice to be able to run zfs on such small memory,though saw someone mention something regarding writes and block size,so if turn off performance=all and just metadata it would result in much heavier write operations on disk?18:39
sdezielvlm: the ARC is mostly (exclusively?) for reads18:40
sdezielvlm: I'm not advising to tweak primarycache blindly. This should only be done if you feel the ARC doesn't shrink enough when there is memory pressure18:42
vlmsdeziel: considering adding some maybe,ill see how it turns out first18:43
sdezielvlm: I would suggest you run with stock default params for a while and then only try to fine tune a thing or two. The ZFS folks have worked hard to get good defaults and they know their stuff way better than I do18:43
sdezielvlm: ZFS will happily take all the RAM you throw at it but it can accommodate surprisingly well with very little too.18:44
sdezielvlm: how much RAM do you have and how much data are we talking about?18:45
sdezielBTW, the arc_summary script will show you a lot of nice stats if that interest you18:45
vlmsdeziel: im about 4GB though i got a lot going so think im free about 1-2GB18:46
vlmsdeziel: im off abit thanks for all the usefull information that script also very informative,ill do some reading on info zpool aswell whole other world this compared to mdadm -_-18:49
sdezielvlm: you are welcome18:49
=== ijohnson|lunch is now known as ijohnson
sveinseI'm running 18.04 server and I'm setting up ipv6 with SLAAC and I need the server to generate a stable IP address. I notice that my ubuntu 18.04 and 20.04 does this out of box, but the server does not. Where might I find more info about this?20:24
sveinse*my ubuntu 18.04 and 20.04 desktop20:25
RoyKsveinse: you can turn off ipv6 privacy extensions - that'll make the SLAAC address based on the MAC address20:59
RoyKsveinse: very useful if privacy isn't relevant20:59
RoyKsveinse: I used that for a bunch of infoscreens running off raspberry pi machines, the hostpart of their ip defining the machine and the webserver using that to serve the correct data21:00
RoyKeasy peasy :D21:00
sarnoldRoyK: ooo that sounds neat21:01
RoyKsarnold: scales well too ;)21:03
sveinseRoyK: my ubuntu desktop creates two ips, one "temporary dynamic" and one "dynamic mngtmpaddr". And I believe the latter is a stable IP but still using the priv extensions. This is what I want for my server too.21:04
RoyKsveinse: for the server, I'd use a static IP, not SLAAC, but then, that's perhaps just me (although I doubt it's "just" me)21:08
RoyKremember that if you choose a SLAAC address for a server and the server is replaced, it'll get a new IP. Just use a static address for those. It's easier unless you have a *lot* of servers to manage, in which case there are other ways to sort it out21:10
sveinseRoyK: yes. I want to skip setting up DHCPv6, and nor do I really want to set static IPs on each server. So I would have hoped SLAAC could save me the trouble, but I do indeed see the contradiction is what I want to achieve21:12
RoyKsveinse: may I ask what sort of environment this is?21:14
sveinseI wonder which is least troublesome DHCPv6 for central config of IP addresses or on each of the servers :D For ipv4 its central DHCP today21:15
RoyK(probably up north, so that dhcpv6 will freeze during winter)21:15
sveinseRoyK: A small office network. Around 20-ish servers with fixed ip21:16
RoyKthen it might perhaps be just as much work setting up dhcpv6 than setting dhcpv6 addresses manually? ;)21:17
sveinseFor some unexplained reason I have a mental impression that SLAAC is better than DHCPv6 due to it being stateless. Thus for most clients and users, I do want SLAAC for them.21:18
RoyKnot as fancy, but if set manually, it'll work regardless of the dhcp server running or not21:18
sveinseThe reason for having ipv4 DHCP assignment of static resources is because then the dhcp server is the one stop shop for assignments21:18
RoyKwe still stick to static ip addresses on servers at work, and we have a wee bit more than 20 servers21:19
sveinseRoyK: yeah, another company with 1400 employees does that too on its servers21:20
RoyKsveinse: I work for oslomet21:20
sveinseRoyK: oh, cool, this is in Stavanger21:21
RoyKI guessed somewhere in .no by your name and ip :)21:21
sveinseMay I ask if you use any of the link ips, fe80::, for anything for the network infrastructure? Or only the global scoped ips?21:23
sveinseI noticed that windows tend to use fe80:: as default GW, while linux use the global21:24
RoyKI'm not sure about that, as for default gateway or similar. there might be something out there. I haven't worked too much with the networking details21:24
sveinseok, thanks21:24

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