On 2017-02-09 08:55 AM, Mario Lobo wrote: > On Wed, 8 Feb 2017 19:08:41 -0800 > Geoff Nordli <geo...@gnaa.net> wrote: > >> On 2017-02-08 06:11 PM, Mario Lobo wrote: >>> On Tue, 7 Feb 2017 12:02:24 -0800 >>> Geoff Nordli <geo...@gnaa.net> wrote: >>> >>>> Hi Mario. >>>> >>>> I use the pause quite a bit to backup virtual machines. Pausing the >>>> machine will flush the cache and complete all outstanding async IO. >>>> >>>> https://www.virtualbox.org/pipermail/vbox-dev/2011-June/009810.html >>>> >>>> Look for the ignoreflush property and set that. >>>> >>>> VBoxManage setextradata "name" >>>> \ "VBoxInternal/Devices/ahci/0/LUN#[x]/Config/IgnoreFlush" >>>> >>>> As a note, I use iscsi targetsand zfs/solaris to host the data as >>>> zvols. >>>> >>>> Snapshots aren't 100% guaranteed. If you have applications like >>>> Exchangeconsider using something like VSS on Windows. For example, >>>> with Exchange I use VSS and then snapshot the disks from inside the >>>> the VM using putty/plink. Then I know I am getting a good copy of >>>> the data. >>>> >>>> Other applications may havereplication options. >>>> >>>> For things like SQL, I use a separate backup application to >>>> explicitly backup the database, just to make sure. >>>> >>>> >>>> Geoff >>>> >>>> >>>> >>>> On 2017-02-06 03:36 PM, Mario Lobo wrote: >>>>> Hi to all. >>>>> >>>>> Currently, my backup routine consists of shutting down all VMs, >>>>> copy all their .VDI files to the standby server, and restart the >>>>> VMs. >>>>> >>>>> The obvious reason is for the standby server to be ready to run >>>>> the VMs in case the primary server fails. >>>>> >>>>> A few questions comes to mind: >>>>> >>>>> 1) Shutting down and restarting the VMs is always a lot of work, >>>>> no to mention the loss of counters, system statistics, etc ... >>>>> so, is it safe just to pause the VMs to copy the .VDIs over? >>>>> Would a paused state .VDI start ok on the standby server if I >>>>> need to fire it up? >>>>> >>>>> 2) What is the proper procedure to backup via snapshots to a >>>>> standby machine that needs to be fully independent of the primary >>>>> server? >>>>> >>>>> Any experiences or recommendations are gratefully welcomed. >>>>> >>>>> Thanks, >>>>> >>> Thanks for replying, Geoff! >>> >>> It made sense to me that pausing would be ok but I needed to confirm >>> this. >>> >>> One last question. >>> >>> Sounds wierd to me to set an IgnoreFlush property if pausing the >>> machine will flush the cache and complete all outstanding async IO. >>> >>> Is this setting telling the VM not to flush? >>> >>> Is this IgnoreFlush a per VM stting or general? >>> >>> Thanks again. >>> >> Here is some more information on the ignoreflush property: >> >> https://unixsherpa.com/solution/honor-guest-idesata-flush-requests/ >> >> It is based on the device and it just tells vbox to not lie to the OS >> that data is has been saved to improve performance. >> >> I also disable caching in vbox on the controller. >> >> I do all my caching in zfs where I know the data is safe. >> >> Geoff >> > Do you mean to uncheck the box "Use Host I/O cache" on each controller? > > Yes, I make sure that it is off. I actually think it is off by default because it was causing VMs to hang if it couldn't keep up with IO.
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