aarcee74 aar wrote: > Thanks Jim for the reply , Yes i did had a look at the settings , but > i assume that is more towards AIX5.2 and 5.3 has many changes as > compared to 5.2, especially with memory handling.So i was just > referring whether any other changes are reqd with 5.3 , related to > jBASE . Yeah, but a lot of the information generally holds true.
> > In the case of SAN, we use EMC, symmetrix and Clariion disks and i am > sure that the performance is pretty good if we take jBASE out of the > picture. A simple tar and compress itself is giving me 60-70MB /s and > normal "dd" commands also giving me asimilar throughput. I need to > verify everything from the server side , before going to EMC for > clarifications...! That suggests that you need to do a lot more tuning of the Clariion system to be honest. 70MB/s is pretty weak for all that hardware. I have tow $180 SSD drives on my Linux system and I get up to 160MB/s without any tuning. If that's the best the SAN can do, then I would not use it. To be honest I have not seen anything but performance and reliability issues with SANs (regardless of jBASE). > > Is there any direct relationship to the modulo which is being used to > create a file and the I/O which it makes when the file is accessed ? Remember that your tar and dd are the fastest way you can read and write to the file system as they produce sequential IO, which quickly turns in to track reads. So, no database accessed in any random manner will get anywhere close to sequential track read performance. The best you can do is to write a small program in jBC that does a SELECT (a jBC SELECT not an EXECUTE) then READNEXT through the file in a tight loop. The drivers should pick that up as sequential IO. Now, how the SAN translates this into its own access patterns is anyone's guess. It is a riddle wrapped in a mystery inside an enigma. As far as I have been able to determine in the past, sequentiality of disk blocks does seem to hold somewhat, but all the different layers in the system significantly blur what is going on. In short, before even worrying about jBASE you need to download one of the disk performance testing programs, compile it on AIX and get a baseline for sequential and random IO. Then try the same on a local disk/disk array. Once you have that, then you can tune the SAN in whatever ways it allows (but lots of local RAM given to disk buffers is going to help). Having done that, then you can test the kinds of things your program does. Make sure that your files are well sized (which seems to mean not using jrf on jBASE 5 :-(. > > Also, one more query, we have found that the jBASE/T24 is not making > use of SMT, the second logical thread for the CPU. Is it that > something needs to be compiled again. > See Pat's earlier reply about jBASE. --~--~---------~--~----~------------~-------~--~----~ Please read the posting guidelines at: http://groups.google.com/group/jBASE/web/Posting%20Guidelines IMPORTANT: Type T24: at the start of the subject line for questions specific to Globus/T24 To post, send email to [email protected] To unsubscribe, send email to [email protected] For more options, visit this group at http://groups.google.com/group/jBASE?hl=en -~----------~----~----~----~------~----~------~--~---
