Hi everyone, I've run into som substantial read degredation when using dump or tar to backup filesystems that are stored on LVM2 LVs. Many times in the past I have seen dump run at speeds approaching block device speeds; 50-60MiB/s, similar with tar. I'm seeing speeds in the range of 3-4MiB/s when dumping a filesystem. If I increase dump's blocksize to 128KiB records, speed jumps up to about 20KiB/s, which is better but still frustratingly slow. Going to 1024KiB gets me about 28MiB/s. Is this amount of performance loss expected? My LV is just two SATA hard disks that I put into a VG. Stupid benchmarks with dd gives me a raw read speed from the LV of about 60MiB/sec. Any ideas on what's slowing down dump? -- Ross Vandegrift ross@kallisti.us "The good Christian should beware of mathematicians, and all those who make empty prophecies. The danger already exists that the mathematicians have made a covenant with the devil to darken the spirit and to confine man in the bonds of Hell." --St. Augustine, De Genesi ad Litteram, Book II, xviii, 37 _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
