Disk (and Other Resource) Management Of Virtual Machines

I am using libvirt and kvm to run virtual machines. I would like to be able to change the size of the virtual filesystems and snapshot them (in the sense of snapshotting the disk for backup. Ideally this would be a snapshot of part of the file system, not the whole disk). Any recommendations for how to accomplish this?

In the past, using KVM alone, I have carved logical volumes out of volume groups on the host system and exposed them as raw disks to the VM‘s. The current host has a large LVM volume group on top of an encrypted software RAID.

Is there a way to expose host file systems to the guests? NFS is a possibility, but the VM’s will be running various services that warn not to use NFS. libvirt doesn’t seem to provide the ability to expose host file systems directly (as opposed to exposing raw block devices), but I’m hoping I have missed something.

I could run LVM inside the VM’s; this would provide somewhat more flexibility and disk snapshotting, though I’m not sure how I would provide more total space to the VM in this scenario. But it seems ugly to be running a virtual LVM on top of the host LVM.

Finally, could anyone clarify the VMs in this libvirt/KVM setup use CPU and RAM resources? If I give a guest machine 4G of RAM does that mean that memory is unavailable for other use by the host or other guests? virt-manager has configuration for memory and maximum memory, suggesting that at least some dynamic growth is possible. Likewise, if the physical machine has 8 cores, could I run several VM’s with 8
cores each? My suspicion is that CPU’s are shareable, but RAM is not, but I don’t know.

Thanks. Ross Boylan

P.S. I don’t need to be able to make the changes while the VM’s are live, though the ability to do so would be handy.

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USB Drive Mounted Read-only; What To Do ?

I plug in a USB pen drive, and launch dd to copy an iso image.

# dd bs=4M if

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Loading Debian 7 On Pentium E5300

I am trying to install Debian 7 on a machine running the E5300 chip. I
believe the amd64 is the correct choice but the system will not recognize the disc, I’ve redone the first disc on another fresh disc with no luck. I tried i386 and it installed fine but then did not work correctly. Other software I insert in the machine is recognized but the amd64 ISO is not recognized. The amd64 version is on the same batch of discs that load up i386 version just fine so I think the type of disc is not the issue. Any help on this?

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Broken Apt ” -f Install” Wont Fix What To Do ?

Hi all,
when you have an error of apt-get

which recommends -f install
which could not be fixed using it is there a kind of procedure to repair it ?
untranslated quote:

2 Comments


Contract Full Stack Software Engineer – San Francisco

Contract Full Stack Software Engineer – San Francisco

- Positions: 1
- Type: Contract/hourly
- Location: San Francisco, ca (newr Chinatown)
- Duration: 12-months
- Rate: to 70/hour dep. on exp. W2
- Citizenship: Required. Green Card Ok
- Telecommute: None

Our San Francisco client located near Chinatown is focused on new media content generation with a special focus on comedy programming. They build web-based and mobile interactive systems to capture, manage, package, and distribute audio and video based content. They are actively seeking seasoned full stack developers and architects to build the next-generation platform. These are very much hands-on systems engineering and applications development roles using the latest technologies to craft scalable, highly reliable and secure systems.

Responsibilities:

* Write server-side code for web-based applications
* Work collaboratively within a multi-disciplinary team to create practical solutions to real-world problems, but be comfortable leading sprints with limited oversight
* Manage and support existing Java-based production systems while migrating key concepts into new platform in firmwide technical ecosystem

Minimum qualifications:

* BS in Computer Science or related technical field or equivalent practical experience
* 5 years of relevant work experience including deployed web-based systems development, with deep understanding of Unix/Linux

Preferred qualifications and skills:

* 8 years relevant work experience including Java, relational databases, web systems
* Specialized skills: Internal Amazon technical ecosystem, Secure software development, MySQL, Maven, Spring Framework, Hibernate, HTML5/CSS, JavaScript, JSON, REST, jQuery, AngularJS
* Audio/video/image processing

To be considered for this opportunity, please submit your resume and hourly rate to dan@swift-staffing.com

Thank you, Dan Swift

http://swift-staffing.com dan@swift-staffing.com


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Is Sshd Really Restarting?

Setup: very new install of gentoo

When I restart SSH like so:

sudo /etc/init.d/ssh restart

I see very little output. Should it be more verbose?

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7 Comments


Easiest Way To Shut Down All Network Services Besides Ssh?

I have a system that I would like to make accessible only by ssh.

No apache telnet ftp anything else.

What is the easiest way to achieve this? It came from a vendor with a slew of package of all sorts, so I don’t even know everything that I want to remove.

Thanks, Britton

8 Comments


Help On Linex

i had linex OS&windows7 professional.By some careless mistake windows7
is not appear.when i power on it shows four version of OS &windows vista(loader) instead of windows7&linex.all the four verion of linex are still working but the windows vista(loader) is not opens it requires setup.please help me to access my windows7&linex.

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Problem With AFS Token And Sudo In Jessie

Dear all,

I’m using Debian jessie with openAFS and Kerberos. I found a strange behaviour that I could not pin down to a single package so far, maybe somebody has any ideas:

The AFS token is gone after using sudo, first looking very similar to the (solved) bug #621496 from 2011. After each sudo command, one needs to use “aklog” to get a new AFS token.

Yet, I suspect that the bug is different from the 2011 one:

First, it not only happens for passwordless sudo, but also when the user is forced to enter the password.

Second, I have a PC running with Jessie that does not show this bug -
this Jessie wasn’t upgraded for some time (around September 2014). Another PC which is up-to-date shows this bug, as well as a new installation I did recently (which is also up-to-date). The config files or our Kerberos/AFS setup did not change since I setup this PC, only the packages were upgraded with apt-get. The problem now is: The version of the libpam-afs-session package is the same in the working and the non-working image.

In addition, I selectivly upgraded the openafs-krb5 and the openafs-client as well as openafs-modules-dkms to the most recent version in Jessie (the “starting point” see below). This did not introduce the bug – sudo is still working as intended.

Since I’m not too familiar with AFS/Kerberos/PAM I decided to ask you if you have any ideas what I could try to pin down the reason for this? Any packages to upgrade to see if they are responsible for this?

If I should provide more details / config files / information, please let me know. I’ll see if I find the time to do a test setup with sid to check the newest version of the packages, but maybe my problem is far easier and somebody knows what to do.

Best regards, Christoph Schober



The following versions are from the (older) working image before starting selective upgrades:

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Jessie: Samba/cifs Ls Rsync Unusably Slow (lstat)

Dear all,

after upgrading to jessie I have a serious problem with a cifs mounted Windows share:
Directory listing is extremely slow. ls of a large directory can take several minutes, rsync comparison of directories (lstat call for every file) needs 30+ minutes (with wheezy: 23 seconds). I tried downgrading samba and/or rsync to the wheezy versions but it did not help. Up- and downloads are still as fast as before, it’s the same hardware as before. Any ideas what else I could try?

Best regards, Christian

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