Quoting Gareth Bult (gar...@linux.co.uk): > Mmm, there has been some discussion around this .. > > Technically using cache=writeback "should" be safe for migration. > (which is the method I use) > > So .. I need "cache=writeback" and "sharable" for migration to happen. > (the performance hit with cache=off is an unacceptable performance hit, at > least for me ..) > > From the QEMU lists, 2012; > "In short, if you're using a recent kernel with ext3 or ext4, cache=writeback > is absolutely safe. If you're using an older version of ext3, cache=writeback > is still safe but ext3 itself isn't. cache=writeback can make the situation > worse."
Hmm, the guys at big blue think otherwise [1]: With caching set to writeback mode, both the host page cache and the disk write cache are enabled for the guest. Because of this, the I/O performance for applications running in the guest is good, but the data is not protected in a power failure. As a result, this caching mode is recommended only for temporary data where potential data loss is not a concern. Gr. Stefan [1]: http://pic.dhe.ibm.com/infocenter/lnxinfo/v3r0m0/index.jsp?topic=%2Fliaat%2Fliaatbpkvmasynchio.htm -- | BIT BV http://www.bit.nl/ Kamer van Koophandel 09090351 | GPG: 0xD14839C6 +31 318 648 688 / i...@bit.nl _______________________________________________ Users mailing list Users@lists.opennebula.org http://lists.opennebula.org/listinfo.cgi/users-opennebula.org
