Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Possibly related to my earlier post, but this time I focused on two things primarily: SSDs and metadata. Hardware: DRBD on top of 1 X25-e in each of the DRBD nodes, configured as simple volume on a hardware raid controller, and connected via IP over infiniband. Workload: 100% random io writes, 8KB block size Direct to the disk: 77.78MB/s, average latency 2ms Disconnected DRBD, metadata on ramdisk: 75.64MB/s, average latency 2ms Connected DRBD, metadata on ramdisk: 50.87MB/s, average latency 4ms Disconnected DRBD, metadata internal: 6.25MB/s, average latency 39ms Connected DRBD, metadata internal: 6.20MB/s, average latency 39ms Disconnected DRBD, metadata on a single 15K sas disk: 43.46MB/s, average latency 5ms Connected DRBD, metadata on a single 15K sas disk: 39.32MB/s, average latency 5ms Full resync speeds for all tests were 180-200MB/s (about what's expected from a single x25-e). There is no difference between flexible and regular metadata for internal or external usage (metadata was recreated for those tests). Interestingly, ~6MBs is the same speed that I got when testing a 7 disk raid 0 15K sas array with internal metadata (everything else is the same) and putting metadata on ramdisk moved that up to ~35MB/s. So for some reason even in the case of a very fast SSD, internal metadata performance for random writes is really bad. Putting it on any kind of external disk brings an immediate exponential performance increase.. -Gennadiy -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20090508/8f39521d/attachment.htm>