Bowie Bailey spake the following on 10/12/2006 1:22 PM: > I have two identical servers. The only difference is that the first > one has Maxtor 250G drives and the second one has Seagate 320G drives. > > OS: CentOS-4.4 (fully patched) > CPU: dual Opteron 280 > Memory: 16GB > Raid card: 3ware 9550Sx-8LP > Raid volume: 4-disk Raid 5 with NCQ and Write Cache enabled > > On the first server I have decent performance. Nothing spectacular, > but good enough. The second one has about 1/3 the write speed. I > can't find any difference between the systems. Both of them have the > same stripe size, both have ext3 filesystems, both have write caching > and NCQ turned on. I have already increased the read ahead setting to > 16384 on both servers. > > I ran the tests like this: > > # sync; bonnie++ -d /iotest -s 50g -n 0 -b -f > (I have removed some extra information from the reports for brevity) > > And here are the results for the two servers: > > ------Output------- --Input-- > --Block-- -Rewrite- --Block-- --Seeks-- > Machine Size K/sec %CP K/sec %CP K/sec %CP /sec %CP > First 50G 62893 25 46763 12 160672 19 120.6 1 > Second 50G 18835 7 44025 12 194719 24 122.8 1 > > As you can see, the write performance of the second server is > terrible. Anyone have any suggestions of what I can look for? I keep > thinking there must be something I tweaked on the first server that I > forgot about for the second one, but so far I haven't been able to > find it. > > Any suggestions appreciated! > Is there a difference in the write performance, speed, or cache size of the drives? You didn't list specifics of the drives, so I had to ask. -- MailScanner is like deodorant... You hope everybody uses it, and you notice quickly if they don't!!!!