How to upgrade a FreeNAS installation with a running iSCSI share?

[viniciusferrao]

Hello guys,

I've a FreeNAS server with 24 disks running a single pool for iSCSI sharing with VM's inside.

Now with the constant FreeNAS updates it's becoming a little frustrating to upgrade the software. Since I don't have any other storages I must shutdown all my VM's to update the system an them restart everything. So a downtime period is needed.

I doing this procedure just to be safe, but I would like to know if it's possible to update the FreeNAS installation and reboot the server without disabling the iSCSI connections. I'm aware that when I reboot the server the iSCSI communication will be ended, but the point here is to know if the software is smart enough to reestablish the connection when it come back.

If yes the update process will be much more straightforward.

Thanks in advance,
Vinícius.

 

[mav@]

VMware is usually ready to wait for some time for iSCSI connection to restore, but this wait time is not very long. After server reboot it will happily reconnect, but whether VMs survive up to that time -- depends. Somebody told me that this wait time may be configurable on VMware side, but I haven't checked.

 

[viniciusferrao]

VMware is usually ready to wait for some time for iSCSI connection to restore, but this wait time is not very long. After server reboot it will happily reconnect, but whether VMs survive up to that time -- depends. Somebody told me that this wait time may be configurable on VMware side, but I haven't checked.

Although I'm not using VMware, this information is valuable.

I will check if Citrix XenServer (the hypervisor I'm using) have manageable timeout tolerance for iSCSI.

Thanks,



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[Nick2253]

It's configurable, but only up to a point. Ultimately, it depends on the guest OS, and even though you may be able to set the timeout to be very long, it's not always the best idea, and some OSes (*cough* Windows *cough*) can be kind of temperamental.

I know these docs are from VMware, but they give you the important steps for the guest OSes:

You can set the Windows timeout value in the registry: https://pubs.vmware.com/vsphere-51/index.jsp?topic=/com.vmware.vsphere.storage.doc/GUID-EA1E1AAD-7130-457F-8894-70A63BD0623A.html

For Linux systems: http://kb.vmware.com/selfservice/mi...nguage=en_US&cmd=displayKC&externalId=1009465

EDIT: The long-and-short of it is that you don't need to update FreeNAS. If it's working, don't break it. And, when you get the opportunity to do proper downtime, I'd do the upgrade then. You'll know if you need to do a critical update for security reasons because you'll get the regular update notices from your box if you have the email set up correctly.

 

[mav@]

I have no idea about Xen, but feature of VMware here is that when it looses connection to storage, it start returning SCSI BUSY status to its guests (try again later) to prevent them from really timing out. While it may still be not a full panacea (FreeBSD guests up to some version still returned error after several retries), it converts the situation from timeout to more controllable number of retries, that for BUSY status can easily be infinite. On my experiments I've made FreeBSD on VMware to wait for storage for more the an hour. :)

 

[cyberjock]

No, this won't work. If you want that kind of tolerance from a system reboot you must buy TrueNAS with HA support.

For FreeNAS, there is no "workaround" for rebooting except to force VMWare to have a stupidly long time to give up (like 10 minutes). This can create major problems and can create other much bigger problems.

The short is that you (like me with my iSCSI setup) must shutdown the VMs to do a FreeNAS upgrade. In convenient it is, but unfortunately there is no "workaround" for this problem.