Tab, Personally I prefer AIX. And I know there are going to be some Windows bigots who disagree with everything I say about Windows, so I am going to qualify my remarks by saying that as a consultant I have worked in a wide variety of environments from small to large with all different flavors of OS's so my comments are based on my experiences. But having stated that, let me offer a few things for you to consider. First I am going to discuss the Windows environment using 32 bit Windows which will have some serious limitations. I believe that is what you are intending to do since you didn't specifically state other wise.
One major problem is that W2K3 does not have good memory management, in fact the TSM server process will only be able to see/use 4GB of memory. That means any memory beyond 4GB is not used at all by TSM, however if you are running multiple instances of TSM or you are running the ISC/AC on the machine it maybe useful to have more memory. Now back to the 4GB memory for the TSM server, 2GB is used by the kernel right off the top, which means that you can only get about 1GB for the BUFPOOLSIZE. The rest is needed by the the TSM server code and any other overhead required by the process. If your DB requires a larger BUFPOOLSIZE to perform well you may be out of luck! Another thing to consider is concurrent I/O (network and disk), Windows based machines as you stated a clearly lacking in this area. I notice it particularly when I am trying to backup many nodes at the same time. Once I get above 20 to 30 sessions I start to notice that my "Pct. Comm. Wait Last Session" values start to go very high even though the overall bandwidth is not maxing out the network connection, i.e. 30-40 MB/sec across a 1Gb network. Where as on a comparable AIX system I can run 3 or 4 times the number of sessions with no noticeable degradation in the Comm. Wait times. This is mostly due to poor TCP/IP performance of Windows based machines, single sockets are fine but open 30 sockets and try to pipe data through them and you will be slow! Now lets talk about disk I/O. One thing the Windows version of TSM has going for it is that it is very quick to build DB, LOG and Diskpool volumes. This is because it doesn't initialize them like it does on AIX which can take quite a while if you are building large volumes, but how often are you really creating these volumes. Disk I/O performance to like SAN hardware is pretty close in both machines. However, again when doing many current data streams the AIX environment always outperforms the Windows one. Not as big a difference as the networking issues but still noticeable. Performance monitoring and tunning is another area of concern. There are reasonably good monitors for both environments. No matter whether it is memory, network or file I/O performance tuning in an AIX environment is much more flexible and far easier to do. To be fair, Windows in small environments often performs quite well with no extraordinary tuning required. AIX on the other hand usually will require some tuning to get it to perform well. In larger environments AIX will require a bit of tuning to make sure it is running optimally, but for Windows there just doesn't seem to be enough tuning to get it running as well as it should in large environments. In summary I will say that Windows based machines are fine for small to medium size environments. When you get to the top end of the medium and into the large environments I think you should consider a machine that can handle the kind of I/O you are needing to pump through it. I think from the description of your environment that you are a medium size environment, but like everyone else you are probably growing. You might want to consider this that for the price of a Quad Xeon system you could easily afford to get a new 2-Way P5 (i.e. a P5 520) which would clearly out perform the Xeon based machine. Also, the P5 520 would allow for future growth. -- Regards, Mark D. Rodriguez President MDR Consulting, Inc. =============================================================================== MDR Consulting The very best in Technical Training and Consulting. IBM Advanced Business Partner SAIR Linux and GNU Authorized Center for Education IBM Certified Advanced Technical Expert, CATE AIX Support and Performance Tuning, RS6000 SP, TSM/ADSM and Linux Red Hat Certified Engineer, RHCE =============================================================================== Tab Trepagnier wrote:
We are considering migrating our TSM systems from AIX to Windows 2003. I know that the experience of the forum participants is that AIX provides superior I/O performance, but where is that threshold? These are our system details. I'd like for anyone with experience with a system of similar size to share their experiences regarding Unix vs. Windows. We are currently running TSM 5.1.10 on a 2-way 6H1 with 4 GB RAM. We are considering running TSM 5.3.2 on a 2-way or 4-way 3.0 GHz Xeon with 4 GB RAM. All non-OS I/O would be via GigE network and redundant 2 Gbs fiber. TSM system details: DB: 32 GB @ 83% utilization Log: 5 GB, roll-forward mode Primary data: 16 TB with one copypool (another 16 TB to manage) Nodes: 175 backing up during a 10-hour window Average daily incoming data: ~ 200 GB; may be reduced via deployment of TDP Oracle Disk: 1 TB DAS, 3 TB SAN Tape: LTO-1, DLT8000, 3570XL, four SCSI drives each; libraries will be consolidated Daily copypool updates sent to vault Semi-annual exports in the 2-5 TB range Does that sound like a system that could reasonably be hosted on a modern Windows system? Is a 2-way adequate, or should we get a 4-way? Thanks in advance. Tab Trepagnier TSM Administrator Laitram, L.L.C.
