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Re: SSHD (and steam and windows and other stuff)
by Russell Coker 14 Jan '16

14 Jan '16

On Wed, 13 Jan 2016 08:43:28 PM Craig Sanders via luv-main wrote: > On Wed, Jan 13, 2016 at 01:28:57PM +1100, Trent W. Buck wrote: > > AFAICT the only reason SSHDs exist are: > > * Windows has nothing like bcache/l2arc; or > > it does. it's called ReadyBoost. Compared to bcache/flashcache or L2ARC > for ZFS, it sucks. You can't just tell Windows to use an SSD (or > partition thereof) to cache an arbitrary disk....well, in theory you > can but in practice Windows itself decides whether that option will be > available by its own inscrutable and undocumented method. https://en.wikipedia.org/wiki/ReadyBoost ReadyBoost is described as supporting USB Flash, CF, and other storage systems. USB Flash is notoriously unreliable and has given flash storage a bad reputation. It seems to be only read caching, it would be ridiculous to consider devices like USB Flash for write-back caching. > I discovered this just last week after upgrading my win7 games box to > have an SSD as a boot disk, decided to try ReadyBoost for my main 2TB > steam library drive (not an SSHD) so made a 40GB partition for it. No > matter what I tried, I couldn't get windows to make the option available > in its Disk Manager GUI - it was there, just greyed out. As you noted later in your message SSD storage in the TB range is getting quite affordable now. If you are buying an expensive gaming PC then getting 1TB of SSD for all your favourite games isn't going to change the price much. 2TB of SSD is in the range that many middle class people are prepared to pay. There doesn't seem to be a good case for MS to invest in further development of ReadyBoost. I don't like the idea of Bcache. What I would like to do is to be able to tell BTRFS to use certain disks for metadata only. For example I'd like to have a server with the root and /home subvols on a RAID-1 pair of SSDs as well as the metadata for all other subvols. Then have all the bulk data on a pair of large SATA disks. For my home fileserver I have no performance problems with tasks such as NFS serving big MP4 files (like my collection of FullHD music videos downloaded from Youtube), but I do have performance problems with ls. Also my home server has backups of a number of other systems (including the LUV server). When I run rsync without the -c option metadata access is a major bottleneck. > Microsoft seems to have abandoned the ReadyBoost idea. and they seem to > be confused about what SSD caching of hard disks is good for - their > documentation is all about how it might help on low-memory machines > (<4GB), presumably because they don't have enough RAM to cache large > chunks disk in RAM. as bcache etc on linux prove, SSD caching is > beneficial even on machines with lots of RAM. It really depends on what you are doing. A SSD read cache provides no benefits if the working set of the applications that are running fits in RAM once the system has been running for a while. For example the LUV 524M of storage for all MySQL databases and probably less than 100M of other data that is used often. It has 2.5G of RAM so it does hardly any disk access apart from synchronous writes for the mail queue once it's been running for a while. > windows is so damn primitive and restricted. i can't understand how > anyone could possibly think it's any good or that it makes a decent > desktop environment. it's almost unusable in its awful crappiness. i'm > glad i only have to use it as a games launcher. Some people think of a desktop OS as a games launcher, in which case Windows is doing ok in terms of game support. Steam is moving towards Linux which significantly changes things but at the moment Windows is a passable game launcher. > interestingly, i don't even have to use my KVM to switch to the windows > box any more if i don't want to - steam's in-home streaming feature > means that in addition to running native linux games on steam, i can > "stream" windows-only games from my win7 box. that means it executes on > windows but displays on my linux box in either full-screen or windowed > mode. would probably suck on wireless but there's no noticable lag or > performance loss on a wired gigabit network. i'm kind of amazed at how > well it works. That's interesting. > but given that the SSHDs i bought were roughly the same price as > non-SSHDs, i don't see any harm and some potential benefit in using them > on linux. 8GB cache isn't much but it "just works" without any hassle > or configuration. it's giving me some SSD caching on my ZFS 'backup' > pool without having to add another SSD to the same andr dedicate an SSD > partition to the task. For a filesystem like ZFS or BTRFS where the read hot spots move around the benefit of a small amount of read caching is probably small. If they do write caching then that could make a huge difference as the seek patterns for ZFS and BTRFS can cause significant problems. > but if you're not in a hurry to get an SSD, rumour has it that there > will be significant increases in capacity AND reductions in price on > SSDs this year. Just like every other year. ;) -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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SSHD
by Russell Coker 13 Jan '16

13 Jan '16

http://cdn.msy.com.au/Parts/PARTS.pdf https://en.wikipedia.org/wiki/Hybrid_drive https://en.wikipedia.org/wiki/Shingled_magnetic_recording Are SSHDs any good? MSY has Seagate 8TB SSHDs for only $309. That's cheaper than a 6TB disk using regular technology, suspiciously cheap. I'm guessing that they use something like Shingled recording to improve the storage:price ratio and use the SSHD caching to allow decent performance without the OS optimising write patterns for it. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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IPv6 at beginners' SIG
by Russell Coker 12 Jan '16

12 Jan '16

Is there any interest in an IPv6 training session at the beginners' SIG? I'm not volunteering to run it as I don't consider myself an expert on it (and I'm doing lots of other things). But I can help out, the LUV server isn't the first server I've setup for IPv6. Tony would you like to run such a session if there's interest? -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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more about server migration
by Russell Coker 11 Jan '16

11 Jan '16

As mentioned in a previous message (which many people on the list probably didn't get) I've just moved the LUV server to a VM in Germany courtesy of Paul Menzel who pays the rent on the physical hardware. We had a few problems along the way with DNS records not updating when I wanted them to and with the wrong IP address being used for outbound mail - which caused some servers to correctly reject mail on the basis of bad SPF. DNS is now correct and has been correct for long enough that I expect most systems won't have old addresses cached any more (Google DNS has had the new values for a while). Andrew has started the process of gaining control over the DNS (which is registered in the names of people who haven't been committee members for a long time). We need to get that done before VPAC turns things off. My current plan is to use 2 servers that I run for LUV DNS secondaries. I've been a LUV member for 20 years and both the servers in question have been running for that long (one of them hasn't even changed it's IP address). I think that will give some assurance that things will keep working. As an aside if anyone knows how to contact the people running russell.linux.org.au and the creativecontingencies.com DNS servers about changing the entries for LUV then please let me know off-list. When running at VPAC the watchdog table in the Drupal database took up 20G of disk space and as it was in the ibdata1 file there was no good option for freeing the space even after deleting most rows. As part of the migration to the new server I dumped all MySQL databases and imported them. That solved the disk space problem and as I now have MySQL configured for a file per InnoDB table I will always be able to OPTIMIZE TABLE if I have that happen again. echo "delete from watchdog where timestamp < unix_timestamp() - 604800;" | mysql luv_drupal The above command is in a cron job to delete the old entries from the watchdog table. It would be good if we could fix the Drupal problem that's causing those entries (but I don't know how to do it or have time to learn). It would also be good if we could configure Drupal to not store millions of rows in that table (it's supposed to automatically delete old rows but doesn't). Assistance from Drupal experts is welcome. One thing I want to do is to convert the server to BTRFS. BTRFS snapshots is the best way of backing things up. Going forward I want to have much better backups of the server. The fact that I can't visit the server room any more makes them much more important as does the fact that data is crossing jurisdictions. I will resend this message tomorrow to make sure everyone gets it. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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server migration
by Russell Coker 11 Jan '16

11 Jan '16

As previously discussed VPAC no longer officially exists and out hosting there is going to disappear. I have migrated the LUV server to a virtual maching in Germany on the Hetzner network. This gives us plenty of storage, fast Internet access, IPv6, and it's free (courtesy of a German Linux user who is donating the resources). Unfortunately we have some DNS issues. I've got a simple TCP proxy in place for the web server but that doesn't work so well for email as it breaks lots of anti-spam checks. I will use a proxy for the mail server if we don't have DNS sorted out tonight. iptables -t nat -A OUTPUT -d 202.158.218.240 -p tcp --dport 25 -j DNAT --to\ 188.40.100.241:25 If you are eager to send mail to the lists and don't want to wait for me to sort out the DNS problem then run the above command on your outbound mail relay. That will redirect it to the correct destination. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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free Sun 1RU servers
by Russell Coker 08 Jan '16

08 Jan '16

http://www.cpubenchmark.net/cpu.php?cpu=AMD+Opteron+254&id=1806 We have two 1RU Sun servers which each have 2 of the above CPUs. One server has 16G of RAM and the other has 32G. One of them has 2*70G 15000rpm SAS disks and the other has 2*140G. There is also a spare 70G SAS disk. One of the servers is currently in use as the LUV server but that is to be decommissioned. The other is at my home (we used it for the ZFS and BTRFS training). The servers are extremely noisy which is one of the reasons why I haven't done any other training on the server in my home (the other reason being that I have some other servers for this purpose). NB if someone wants to use these commercially then they can buy them from LUV. But they are free for home or non-commercial use. If I don't get any interest then I'll put the RAM and disks in the hardware library and the rest in e-waste. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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One Education project and fundraising (was: Castrated netbook (Windows 10 only))
by Peter Ross 07 Jan '16

07 Jan '16

Hi Trent, thanks. I thought of Chromebooks too. It may be an option. That you need a Google account to boot USB is very understandable;-) BTW: I just found this (when looking for open hardware and remembering the OLPC X0 I bought and sponsored ages ago): https://www.indiegogo.com/projects/infinity-a-computer-anyone-can-build-and… , http://www.one-education.org/ Regards Peter

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Re: Castrated netbook (Windows 10 only)
by Nic Baxter 07 Jan '16

07 Jan '16

On 6 Jan 2016 11:25 am, Peter Ross via luv-main <luv-main(a)luv.asn.au> wrote: > > Hi all, > > I bought a Lenovo Ideapad 100S before Christmas. My old netbook is not reliable (loose LVDS connector inside the glued screen frame, it seems) and I need a lightweight and trustworthy laptop when on call. > > So the idea was installing a proper OS on it but the UEFI is castrated to a point that I cannot even boot from USB (after SecureBoot is off). > > "System does not have any USB boot option" I get if I jump through all hoops and restart with USB device chosen Hi Peter This link claims you can disable booting from the hard drive which allows a fallback to usb booting. http://ubuntuforums.org/showthread.php?t=2285585 Cheers Nic

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Re: automatically starting KVM
by Dan062 05 Jan '16

05 Jan '16

On Wed, 23 Dec 2015 21:18:39 -0500 Jason White via luv-main <luv-main(a)luv.asn.au> wrote: > Russell Coker via luv-main <luv-main(a)luv.asn.au> wrote: > > To run KVM virtual machines it seems to be recommended to un virsh which > > requires XML. > > > I've run kvm guests directly, without virsh installed, while also managing > them from the console. Thus, whether you actually need virsh depends on your > requirements and environment. What you are saying is true, But inmho, virsh give you far more control over the VM (eg: snapshots, connecting devices live etc). While you may be able to do the same without virsh, using it to me is much easier, specially if you are doing it remotely. Cheers, Daniel > > _______________________________________________ > luv-main mailing list > luv-main(a)luv.asn.au > http://lists.luv.asn.au/listinfo/luv-main -- dan062 <dan062(a)yahoo.com.au> -- dan062 <dan062(a)yahoo.com.au>

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No networking and no MATE
by David Zuccaro 02 Jan '16

02 Jan '16

I have accidentally removed some packages from a debian system and now I have lost networking and MATE. Can I reinstall the removed packages from the install cd?

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