- luv-main - luv.asn.au

Re: Melbourne IT - anyone have any contacts?
by piers＠rowan.id.au 25 Jun '18

25 Jun '18

Andrew McGlashan via luv-main <luv-main(a)luv.asn.au> wrote .. > > Sorry I can't help, but I wouldn't recommend Melbourne.IT to ANYBODY, We have one domain with them (which my Dad bought in 2000) and there were two other sites under the same account. One of the other domain owners recovered their domain access and changed the notification email to something other than the company inbox. I will be moving the domain in great haste to a viable provider. I am back up now after 8 calls to the same off shore team who told me they couldn't access the account so someone would call me on Monday. NONE of their web recovery tools worked or even recognised my account or domain. Perhaps it would be wrong to can a company on the Internet but: 1) Their social media chat was a bot 2) They can't run any sort of web services 3) They keep you on hold for 15 minutes and then the call drops (automated?) 4) They tell you that they can't do anything then after 7 calls the same coal face employee can achieve a task. Thanks to those of you who replied; and apologies to those who got spammed this message. Cheers P

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Melbourne IT - anyone have any contacts?
by piers＠rowan.id.au 23 Jun '18

23 Jun '18

Hi there, Does anyone know someone in AU from here? I've got a massive problem because none of their automated stuff works (account recovery, etc) and support can't do anything until Monday. I normally post from another account but it won't work because the expired domain notice was send to an address that was changed and now the lights are out on the DNS. I wouldn't ask if it was important but if you can ping your networks I would be greatly appreciative. If you can't assist then pls forgive this intrusion into your weekend and have a great day! Thanks Piers

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DKIM -- sign all emails on a server, responsible for single or multiple domains, not just remote_smtp?
by Andrew McGlashan 20 Jun '18

20 Jun '18

Hi, It seems to me that DKIM signing is only normally implemented via remote_smtp transport in exim4 of Debian based GNU/Linux. Let's say you have a mail server, it might be for a single domain or it might be for many domains. How do you get DKIM to sign every single email, regardless of whether or not it needs to transit via smtp to another server? If I send to a different domain (or any that the server is responsible for), but without needing remote_smtp transport, then emails don't get signed. I want to do this as I want to use DMARC and force emails to require both SPF and DKIM signing for every email of any or all domains served by the mail server. There are a couple of edge cases too, but I'm not sure I want to go there. One edge case is when you have a device use SMTP to send an alert via an ISP mail server or other mail server that is not trusted with a copy of the private key. The other edge case being emails sent via PHP (with/without Wordpress for example). I've also played around with using a pipe with "Resent-To" facility, not sure I want to sign these, really, as the original author may b problematic; but if I can sign them, then I would use a special selector for that purpose to help protect reputation. Any thoughts? Implementation help? Thanks and Kind Regards AndrewM

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Removing old printer drivers installed as a deb
by Andrew Greig 11 Jun '18

11 Jun '18

Hi All, I have had a pretty crappy run with print drivers on my Ubuntu 18.04 desktop, including one that I got from Epson in England. But today, after accepting the offer to upgrade, my machine jumped from 16.04 to 17.10. But before I could enjoy it it offered the upgrade to 18.04, same as my desktop. But the Printer driver I had installed in 16.04 is now running extremely well in 18.04, same printer, no surprise. So now, I want to remove all traces of the other epson drivers I had installed from deb files. How do I find them, how do I delete them? I will use exactly the same driver as is running so well in my laptop. Can someone point me in the right direction, in RPM land I was fine. But there is better maintenance of GIMP and Darktable in this side of the force. Gratefully Andrew Greig

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Recording from HDMI, is it possible?
by Mark Trickett 04 Jun '18

04 Jun '18

Hello All, >From what I have read and the like, HDMI is supposed to be a "secure" connection that does not allow recording. My experience so far bears this out. I have a Viewer Assist Satellite Television system, the satellite dish, the LNB, and the set top box. That said box is a UEC device, actually a custom Linux box with an infrared remote control for the choice of channel and the like. It has the outputs for component signal to the TV, and HDMI. I used to use it with an old style tube TV, to good effect, but it is now connected to a reasonable LED TV that has the option to record to USB, but will not do so for HDMI input. Is there any way to subvert that, with a PC in the middle, is it even possible to put a HDMI signal into a PC, or is the PC out to a monitor only? Regards, Mark Trickett

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cooperative learning about FOSS via IRC
by Russell Coker 02 Jun '18

02 Jun '18

I think it would be good to try cooperative learning online in the evenings and possibly weekends. The idea is that everyone would join an IRC channel at a suitable time with virtual machine software configured and try out new FOSS software at the same time and exchange ideas about it via IRC. It would be fairly informal and people could come and go as they wish, the session would probably go from something like 6PM to midnight and anyone could just take a break for dinner etc whenever they feel like it. I've got some under-utilised KVM servers that I could use to provide test VMs for network software. The general idea would be for two broad categories of sessions, ones where an expert provides a training session (assigning tasks to students and providing suggestions when they get stuck) and ones where the coordinator has no particular expertise and everyone just learns together (like "let's all download a random BSD unix and see how it compares to Linux"). As this would be IRC based there would be no impediment for people from other regions being involved (hi Rick) apart from the fact that it might start at 1AM their time (sorry Rick). Rick, if you want to run a session then 9AM on a Saturday or Sunday would be a reasonable start time for people here that might be OK for you. While the aims of this would mostly be things that relate to LUV (IE Linux and *BSD) I would be happy to coordinate a session on ReactOS as well. I'm thinking of running training sessions on etbemon, DNS, Postfix, BTRFS, ZFS (maybe with Craig), and SE Linux. I'm thinking of coordinating learning sessions about DragonflyBSD (particularly HAMMER2), ReactOS, Haiku, and Ceph. If people are interested in DragonflyBSD then we should do that one first as in a week or so I'll probably have learned what I want to learn and moved on (but not become enough of an expert to run a training session). I'm also interested in volunteers to run training sessions or coordinate learning sessions. There are some skilled members of this list who never turn up to meetings, hopefully some of them will be interested. Note that the topic doesn't have to be something that interests me, all we need is a trainer/coordinater and a group of people who want to learn. So the issues to be discussed are: 1) What communication method to use? IRC? What server? 2) What time/date for the first session? 3) What topic for the first session? DragonflyBSD? 4) Do we try and make this a mostly-LUV thing or just open it to the world? I wouldn't block random people who want to join, but I also wouldn't necessarily advertise it where people who aren't LUV members would see it. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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RAM sizes
by Russell Coker 24 May '18

24 May '18

https://en.wikipedia.org/wiki/DDR4_SDRAM At the LUV meeting today someone asked me how servers can have so much RAM. Firstly the above page is worth reading, DDR3 (which is in most desktop PCs in use now) can have a maximum of 16G per DIMM, some PCs only have 2 slots, 4 is very common, and 6 is reasonably common for high end systems (I own a couple of those). 6*16G=96G as the theoretical maximum in a high-end DDR3 desktop system and 6*64G=384G as the theoretical maximum of a DDR4 desktop, of course the BIOS or chipset might not support so much. https://en.wikipedia.org/wiki/List_of_Intel_chipsets The above page lists Intel chipsets and gives the maximum RAM supported. A lot of the Core 2 family were limited to 4G of address space, NB that's NOT 4G of RAM, that's 4G including address space for video cards etc - so 3.25G was a common amount of usable RAM on such systems. The Wikipedia page doesn't give information on the RAM limits of the i3/i5/i7 systems. The DDR4 Wikipedia page says that one of the benefits of DDR4 is a maximum module size of 64G. A quick check of my favorite PC parts store showed that they don't sell DDR3 larger than 8G modules or DDR4 larger than 16G (preumably I could get larger via mail order). If I got a motherboard that took 6*DDR4 DIMMs then I could have 96G of RAM, but that would cost me 6*$295=$1770 so I'm not about to do it. http://www.dell.com/en-au/work/shop/povw/poweredge-t640 The Dell page for the PowerEdge T640 says that it has 24*DDR4 slots for up to 3TB of RAM with a caveat that the 128G modules aren't available yet (as an aside it seems like the DDR4 Wikipedia page needs an update in this regard). https://en.wikipedia.org/wiki/Fully_Buffered_DIMM Threre are significant engineering issues related to supporting large numbers of DIMM sockets. The above Wikipedia page is a good place to start if you want to learn about how server RAM is different from (and incompatible to) desktop RAM because of such issues. https://en.wikipedia.org/wiki/ECC_memory https://en.wikipedia.org/wiki/Hamming_code Another difference with server RAM is the use of Error Correcting Codes (see the above Wikipedia pages). Server RAM has extra bits in each word to store codes that allow single bit errors to be detected and corrected and double bit errors to be detected. It's a really good feature to have if you don't want your data to be corrupted. It's also supported in high-end workstation systems and some systems have support for both ECC and non-ECC RAM. ECC RAM is usually "buffered" and won't work in systems that take "unbuffered" RAM (IE all the desktop systems that don't use ECC RAM). There is unbuffered ECC RAM for low-end server systems. Apart from buffered vs unbuffered there's apparently no reason why ECC RAM shouldn't work in non-ECC systems, although when I tried this back in the P4 days (before buffered RAM was invented) it didn't work. One of the more dedicated members of this list got a free server system from LUV and uses it as his personal workstation. It has something like 96G of RAM but makes more noise than most people want in the same building they are in. There's no reason why you couldn't design a system with 24 DIMM sockets that doesn't sound like an aircraft taking off, but most people who want so much RAM have a soundproofed server room. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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Re: Biting the bullet - RAID
by Craig Sanders 24 May '18

24 May '18

On Thu, May 24, 2018 at 03:38:15PM +1000, Paul van den Bergen wrote: > I currently take the approach that unless I have specific IO needs for a > volume, I will work with one partition for OS and data as it is the most > efficient use of disk space. This is true for standard partitioning, or LVM logical volumes. It's not true for either btrfs or zfs. Disk usage efficiency for them is completely unaffected by using multiple sub-volumes/datasets. With partitions or LVs you have to decide how big you want them at the time you create them. Changing their size is a moderately complicated task - not terribly difficult once you know how to do it, but it does require care and attention to detail to ensure you don't screw it up. and depending on the filesystem the partition or LV is formatted with, you may be restricted to only growing the partition, never shrinking it (which makes, e.g., shrinking /home to grow / even more of a PITA) With sub-volumes on btrfs and datasets on zfs, they just share space on the entire pool. Unless you set entirely optional quotas or reservations, you will never have to resize anything. And if you do set a quota or reservation, it's trivially easy and risk-free to change them at any time...they're "soft" limits, not hard. I used to do one big partition for everything - same as you, for the same reason. Now I use zfs datasets so that I can enable different attributes (like compression type, acl types, quotas, recordsize, etc) for specific needs - e.g. mysql and postgres perform better if their files are stored on a dataset where the recordsize is 8K rather than the ZFS default of 128K. And systemd's journald complains if it can't use posix acls, so I'm getting into the habit of setting 'acltype=posixacl' and 'xattr=sa' on /var/log for my zfs machines. And using gzip rather than lz4 for /var/log too. Videos, music, and deb files are already compressed so their datasets have 'compression=off'. Having /home and /var and other directories separated from / is useful - but in the old days of fixed partition sizes, it just wasn't worth the hassle or the risk of running out of space on one partition while there's plenty available on other partitions. Now it's no hassle or risk at all. > synology takes the first slice (~2-3GB) of every disk in the device and > makes a RAID 1 volume for the operating system, then does the same with the > second slice to make a swap partition. You can lose all but one disk and > still have a bootable working machine. the rest of the disk is available > to make volumes out of. yep, this is a good idea. it's similar to what I do on all my machines. craig -- craig sanders <cas(a)taz.net.au>

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Docker for "drivers"
by Russell Coker 24 May '18

24 May '18

After reading the discussion about printer "drivers" (I use quotes due to the different definitions of the term - obviously we aren't talking about kernel drivers here) I've been thinking about how to manage such things. I've used proprietary printer drivers in the past myself, printers are things that sometimes just get added to a network without the sysadmin being consulted (it works for all the Windows systems) and then we are stuck with making them work for so many years that the manufacturer stops providing software updates and it needs shared objects that aren't even supported any more. It seems to me that Docker and similar technologies are a good solution to this. They can encapsulate the shared objects needed (a driver from a badly made .deb or from a .tar.ge won't stop "apt autoremove" from removing things it needs), and deal with architectural issues (I probably don't really need the full overhead of multi-arch just to have an i386 printer driver running on an AMD64 system). Docker etc all have security features that cups lacks which are needed to prevent the (presumably badly written) printer driver from having exploitable security flaws or from just using all memory or disk space. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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Re: Biting the bullet - RAID
by Russell Coker 24 May '18

24 May '18

On Wednesday, 23 May 2018 1:10:08 PM AEST Craig Sanders via luv-main wrote: > far too much RAM to be worth doing. It's a great way to minimuse use of > cheap disks ($60 per TB or less) by using lots of very expensive RAM ($15 > per GB or more). > > A very rough rule of thumb is that de-duplication uses around 1GB of RAM per > TB of storage. Definitely not worth it. About the only good use case I've > seen for de-duping is a server with hundreds of GBs of RAM providing > storage for lots of mostly-duplicate clone VMs, like at an ISP or other > hosting provider. It's only worthwile there because of the performance > improvement that comes from NOT having multiple copies of the same > data-blocks (taking more space in the ARC & L2ARC caches, and causing more > seek time delays if using spinning rust rather than SSDs). Even then, it's > debatable whether just adding more disk would be better. http://www.oracle.com/technetwork/articles/servers-storage-admin/o11-113-si… Some Google results suggest it's up to 5G of RAM per TB of storage, the above URL seems to suggest 2.4G/TB. At your prices 2.4G of RAM costs $36 so if it could save you 600G of disk space (IE 1.6TB of regular storage deduped to 1TB of disk space which means 38% of blocks being duplicates) it would save money in theory. In practice it's probably more about which resource you run out of and which you can easily increase. Buying bigger disks generally seems to be easier than buying more RAM due to limited number of DIMM slots and unreasonable prices for the larger DIMMs. > Compression's worth doing on most filesystems, though. lz4 is a very fast, > very low cpu usage algorithm, and (depending on what kind of data) on > average you'll probably get about 1/3rd to 1/2 reduction of space used by > compressible files. e.g. some of the datasets on the machine I just built > (called "hex"): > > # zfs get compressratio hex hex/home hex/var/log hex/var/cache > NAME PROPERTY VALUE SOURCE > hex compressratio 1.88x - > hex/home compressratio 2.00x - > hex/var/cache compressratio 1.09x - > hex/var/log compressratio 4.44x - > > The first entry is the overall compression ratio for the entire pool. > 1.88:1 ratio. So compression is currently saving me nearly half of my disk > usage. It's a new machine, so there's not much on it at the moment. Strangely I never saw such good compression when storing email on ZFS. One would expect email to compress well (for starters anything like Huffman coding will give significant benefits) but it seems not. > I'd probably get even better compression on the logs (at least 6x, probably > more) if I set it to use gzip for that dataset with: > > zfs set compression=gzip hex/var/log I never knew about that, it would probably have helped the mail store a lot. > (note that won't re-compress existing data. only new data will be > compressed with the new algorithm) If you are storing logs on a filesystem that supports compression you should turn off your distribution's support for compressing logs. That will read and rewrite the log files from a cron job and end up not providing much benefit to size. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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