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Question

Imaging overload?

  • August 15, 2013
  • 35 replies
  • 97 views
D
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We're in the process of attempting to image sets of 31 new 2013 iMac's in school labs all across our district and we're running into a ton of grief..

Has anyone out there experienced problems imaging too many systems at once? When we NetBoot all 31 iMacs at a school and start each one imaging, inevitably a large number (majority) of the systems will fail to install all of the packages correctly. We end up having to do 10 or 15 at a time and then things seems to image more reliably. There is a Mac mini/Promise RAID server at each school providing NetBoot services which also hosts the Casper images locally.

The labs are made up of 31 iMacs all with gigabit network connections back to Cisco switches. Prior labs were made up of 2006 iMacs on 100mbit network connections on older Cisco gear and we occasionally ran into the same problems. Any input or advice would be greatly appreciated!

    35 replies

    RobertHammen
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    • RobertHammen
    • Esteemed Contributor
    • August 15, 2013

    Have not seen this... typically a network bandwidth or throughput issue. Do the network admins have SNMP enabled and/or using any kind of monitoring software (nmap/zenmap) to see exactly what is going on?

    Don't know if it's possible or feasible, but could you utilize a dumb Gigabit switch and patch the Casper server directly into that switch, along with the lab machines? That would confirm that it was a network configuration and/or bandwidth issue.

    M
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    • Matt11
    • Valued Contributor
    • August 15, 2013

    When we used NB we limited it to 10 because even though our Network is huge and fast, something was seeing the NB traffic and throttling it. Redtape aside we just moved to USB sticks.

    M
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    • Matt11
    • Valued Contributor
    • August 15, 2013

    Double :(

    K
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    • Kumarasinghe
    • Contributor
    • August 16, 2013

    Separate the NetBoot service and Distribution points into 2 different servers and test.

    Other thing you can do is to use the RAM Disk method for your NetBoot images to lower the server utilisation as described here;
    http://www.macos.utah.edu/documentation/administration/setup_netboot_service_on_mac_os_x_10.6.x_client.x_client/setup_netboot_service_on_mac_os_x_10.6.x_client-diskless_netboot.html

    Chris_Hafner
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    • Chris_Hafner
    • Jamf Heroes
    • August 16, 2013

    Have you checked the I/O load on your NetBoot server (specifically the Mac Mini not the RAID. We run between 30-50 machines at a time in labs but we made sure that we purpose built our netboot servers to fly at that load. A promise RAID should be fast enough to handle the shadow volumes... Just to make sure, your .nbi is hosted from the RAID correct, not just the DP correct?

    Chris_Hafner
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    • Chris_Hafner
    • Jamf Heroes
    • August 16, 2013

    Have you checked the I/O load on your NetBoot server (specifically the Mac Mini not the RAID. We run between 30-50 machines at a time in labs but we made sure that we purpose built our netboot servers to fly at that load. A promise RAID should be fast enough to handle the shadow volumes... Just to make sure, your .nbi is hosted from the RAID correct, not just the DP correct?

    J
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    • jmercier
    • Contributor
    • June 9, 2014

    I have the same problems ... but it comes down to only 10 machines... with super fast server and network...

    bentoms
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    • bentoms
    • Hall of Fame
    • June 9, 2014

    See http://www.macos.utah.edu/documentation/administration/setup_netboot_service_on_mac_os_x_10.6.x_client.x_client/setup_netboot_service_on_mac_os_x_10.6.x_client-diskless_netboot.html

    J
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    • jmercier
    • Contributor
    • June 9, 2014

    hi

    thats a procedure we already applied on our net boot image...

    i will double check again...

    Chris_Hafner
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    • Chris_Hafner
    • Jamf Heroes
    • June 10, 2014

    I have to ask. Are you running this in multicast? I've seen these problems with other folks if so.

    J
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    • jmercier
    • Contributor
    • June 10, 2014

    hi

    actually im not even sure if im using unicast or multicast... im just imaging basic and standard image from simple net boot... so i assume its unicast

    Chris_Hafner
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    • Chris_Hafner
    • Jamf Heroes
    • June 10, 2014

    In that case I would agree. In general, you have to turn on multicast. Now, with that said, I'm also not sure that NetBoot is your issue as it seems that the machines are booting properly but failing or dropping off during transfer. Diskless netboot is critical, however it will then create shadow volumes on your netboot server. If you don't have the space or the RAM to deal with it along with all the other requests this is the behavior you will see.

    Also a 100Mbit network will slow down the process but it shouldn't kill any of the streams. I've had network segments in the past where there was a 100 Mbit link and it just slowed everything down to a crawl and that's it. Everything kept functioning normally.

    J
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    • jmercier
    • Contributor
    • June 10, 2014

    Hi

    Whats weird... is that back in january with our old installation casper 8.73, everything was fine with the lab... imaging fine etc... now with that casper 9.31 failing.... but only on more than 4-5 machines...

    1-2 machines works fine every time... all the time... my net boot is diskless for sure, and the user have access everywhere on our repository for net boot.

    I also checked our server disk, network, ram utilisation while imaging... the server is mostly asking himself what to do during imaging... nothing much on that side... but on the client side... its 100mb... but i know its been slow past in january but all computers were imaging... not dropping...

    Chris_Hafner
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    • Chris_Hafner
    • Jamf Heroes
    • June 10, 2014

    Interesting. Those numbers are WAY too low. Beyond that I only just realized (after my last post) that you've got everything coming out of a promise RAID. In which case we can discount my mention of storage space (Assuming it's not full).

    Looks like I'm going to have to fall back on the network infrastructure path. There IS something getting in your way. There should be no reason you're limited to such a small number of successful imaging connections. It also may be worth a rebuild of the netboot server just in case. I don't know what anyones upgrade policies are on servers but it's something I NEVER do for these reasons. Regardless, I'm grasping at straws on that one. Only you know how it was set up.

    Do you have someone that can evaluate the connections on the network?

    J
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    • jmercier
    • Contributor
    • June 10, 2014

    i am not getting from promise RAID... im getting that from ATTO thunderbolt to fiber adapter... then this connected to an IBM SAN...

    i have plenty of space... 3TB and 2TB free

    We checked network log and everything on that side and nothing shows up as problems... and the only thing that changed from the last deployment in january and now... is the new server mac pro and casper 9.31...

    i know its a lot but should not be a problem... thats weird considering 1 to 3 machines at a same time works fine...

    Chris_Hafner
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    • Chris_Hafner
    • Jamf Heroes
    • June 10, 2014

    Fair enough... quick question. Which version of Casper imaging are you using on your .nbi?

    J
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    • jmercier
    • Contributor
    • June 10, 2014

    9.3

    Chris_Hafner
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    • Chris_Hafner
    • Jamf Heroes
    • June 10, 2014

    Hrm... there goes another one. I am also running 9.3 I was just wondering because there were known issues with casper Imaging 9.23 through the next few versions. 9.3 was the first safe one I was willing to use. You said your new Mac Pro was built from scratch to host the JSS in January correct?

    J
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    • jmercier
    • Contributor
    • June 10, 2014

    yes... its brand new...

    BUT !!! hey... multicast running now... probably wrong configuration of the casper utility for multicasting...

    its now installing my image... ill let you guys know in couple of minutes... with 1 computer testing... and later today with hole lab... 25 machines...

    Chris_Hafner
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    • Chris_Hafner
    • Jamf Heroes
    • June 10, 2014

    I would be really really surprised if that helps. Then again, I've seen stranger stuff. It will be interesting to hear regardless. Generally multicast is a horrible idea in this circumstance and causes far more issues than it was intended to solve. Yet, any info is good info while we're trouble shooting.

    J
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    • jmercier
    • Contributor
    • June 10, 2014

    welll bad news...

    the client and the server initiate the multicast session... the server sends tons of GB of information... but no data is received on the client...

    Chris_Hafner
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    • Chris_Hafner
    • Jamf Heroes
    • June 10, 2014

    ... wait a min. Are you saying that the client cannot connect to the DP?

    J
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    • jmercier
    • Contributor
    • June 10, 2014

    that's not what im saying... all my clients connects to the DP...

    What im saying is that when i initiate the multicast server, i see my server throwing tons of data on the network...

    then i start my client on net boot and with the multicast restore.sh script... and it stays there forever and no data is copied to the client

    Chris_Hafner
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    • Chris_Hafner
    • Jamf Heroes
    • June 11, 2014

    Ahhh... how interesting. So no success at all via multicast. I'm sure that tells us something but I am certain NOT a network expert. There must be a way to narrow this down. Is there anyway for you to test this on it's own desecrate network? Grabbing a 16 port gig switch and turning on DHCP (assuming that you've got the Mac's DNS service on and pointing to itself) ought to get you there. If it works on 15ish machines on a discrete switch you'll know it's a network related issue.

    J
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    • jmercier
    • Contributor
    • June 12, 2014

    Hi

    i tested 2 machines on simple switch... 1 acting as the multicast server and the other one client...

    The multicast process starts... the server output a lot of data... the client input a lot of data through the network...

    But it never ends !!! it copies and copies and copies data without ending... !!! There is no read write info on the hdd... only on the network...

    and on the client machine... i have this line in terminal and nothing shows up after...

    PSTT 0 100 START RESTORE

    Nothing after that....

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