On Thu, 17 May 2012, Chang wrote: > Hi, > > I was trying to test write performance of Ceph, using direct I/O. > > $ dd if=/dev/zero of=/mnt/ceph/my.dat bs=1M count=1 oflag=direct > > But dd is just stuck without doing any write. > > Without oflag, write is done fine. > > In the above example, I used Ceph kernel module 0.20, built on kernel 2.6.32. That's an extremely old version of ceph. I don't remember when direct i/o became well tested, but it doesn't surprise me that that version doesn't work. I would suggest anything after 3.0... sage > > I also tried Ceph fuse client to mount. > In this case, the above dd command gives me: > > "dd: opening `/mnt/ceph/my.dat': Invalid argument" > > Is it because Ceph does not support direct I/O? > > I'm using ceph 0.46, installed using Debian release package. > There are three OSDs, 1 Mon and 1 MDS in the cluster. > > Any help or clarification is appreciated. > > Chang > > > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
