Messages in this thread | | | Date | Thu, 02 Sep 2010 22:46:35 +0400 | From | Vladislav Bolkhovitin <> | Subject | Re: [PATCH 26/30] ext4: do not send discards as barriers |
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Boaz Harrosh, on 08/31/2010 01:55 PM wrote: >>>>>> An update: I've set up an ext4 barrier testing in KVM - run fsstress, >>>>>> kill KVM at some random moment and check that the filesystem is consistent >>>>>> (kvm is run in cache=writeback mode to simulate disk cache). About 70 runs >>>>> >>>>> But doesn't your "disk cache" survive the "power cycle" of your guest? >>>> Yes, you're right. Thinking about it now the test setup was wrong because >>>> it didn't refuse writes to the VM's data partition after the moment I >>>> killed KVM. Thanks for catching this. I will probably have to use the fault >>>> injection on the host to disallow writing the device at a certain moment. >>>> Or does somebody have a better option? >>> >>> Have you considered to setup a second box as an iSCSI target (e.g. >>> with iSCSI-SCST)? With it killing the connectivity is just a matter >>> of a single iptables command + a lot more options. > > Still same problem no? the data is still cached on the backing store device > how do you trash the cached data?
If you need to kill the device's cache you can crash/panic/power off the target. That also can be well scriptable.
Vlad
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