2014-06-13 11:09 GMT+08:00 Ke-fei Lin <k...@kfei.net>: > Hi list, > > I deployed a Windows 7 VM with qemu-rbd disk, and got an unexpected booting > phase performance. > > I discovered that when booting the Windows VM up, there are consecutive ~2 > minutes that `ceph -w` gives me an interesting log like: "... 567 KB/s rd, > 567 op/s", "... 789 KB/s rd, 789 op/s" and so on. > > e.g. > 2014-06-05 15:47:43.125441 mon.0 [INF] pgmap v18095: 320 pgs: 320 > active+clean; 86954 MB data, 190 GB used, 2603 GB / 2793 GB avail; 765 kB/s > rd, 765 op/s > 2014-06-05 15:47:44.240662 mon.0 [INF] pgmap v18096: 320 pgs: 320 > active+clean; 86954 MB data, 190 GB used, 2603 GB / 2793 GB avail; 568 kB/s > rd, 568 op/s > ... (skipped) > 2014-06-05 15:50:02.441523 mon.0 [INF] pgmap v18186: 320 pgs: 320 > active+clean; 86954 MB data, 190 GB used, 2603 GB / 2793 GB avail; 412 kB/s > rd, 412 op/s > > Which shows the number of rps is always the same as the number of ops, i.e. > every operation is nearly 1KB, and I think this leads a very long boot time > (takes 2 mins to enter desktop). But I can't understand why, is it an issue > of my Ceph cluster? Or just some special I/O patterns in Windows VM booting > process? > > In addition, I know that there are no qemu-rbd caching benefits during boot > phase since the cache is not persistent (please corrects me), so is it > possible to enlarge the read_ahead size in qemu-rbd driver? And does this > make any sense? > > And finally, how can I tune up my Ceph cluster for this workload (booting > Windows VM)? > > Any advice and suggestions will be greatly appreciated. > > > Context: > > 4 OSDs (7200rpm/750GB/SATA) with replication factor 2. > > The system disk in Windows VM is NTFS formatted with default 4K block size. > > $ uname -a > Linux ceph-consumer 3.11.0-22-generic #38~precise1-Ubuntu SMP Fri May 16 > 20:47:57 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux > > $ ceph --version > ceph version 0.80.1 (a38fe1169b6d2ac98b427334c12d7cf81f809b74) > > $ dpkg -l | grep rbd > ii librbd-dev 0.80.1-1precise > RADOS block device client library (development files) > ii librbd1 0.80.1-1precise > RADOS block device client library > > $ virsh version > Compiled against library: libvir 0.9.8 > Using library: libvir 0.9.8 > Using API: QEMU 0.9.8 > Running hypervisor: QEMU 1.7.1 () Answer myself.
The problem was because `bus=ide`, after changing bus type to virtio, everything works like a charm! And `virsh domblkstat` also not showing 512 bytes/sec anymore, it's about 40 KB/s now. Also `ceph -w` shows me a larger number of read per second. Finally, the boot time reduced to 18 seconds. Thanks Andrey, Sage. kfei _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
