Hi Zoltan, First group of questions: What disk type / RAID type / RAID rank / LUN carving strategy is in place? How many paths do you have? What is the queue depth? (Multipath load balancing stragegy?) (And array controller settings too.)
Second group of questions: What disk_group/volume_group striped_plex/striped_logical_volume filesystem/raw_logical_volume type stuff is done to destroy the sequential nature of the I/O. (How many LUNs / how many I/O allowed to pend per LUN?) Third group of questions: Is running one dsmfmt process per file system/plex in parallel and watching the max I/O tell you anything about what the host/subsystem will do under a real backup load? Fourth group of questions: What algorithm does TSM use while figuring out which session gets which volume? What does performance look like during migration and backup stgpool? Fifth group: What does the TSM perf guide suggest? What does the disk vendor's perf guide suggest? Is your environment anything like what the perfs guides are based on? Sixth group: What is good for the sanity of the TSM admin? (50 volumes is nice, 5000 makes the admin crazy?) Is there some common convention, in case someone inherits your environment down the road? [RC] From: Zoltan Forray/AC/VCU <zfor...@vcu.edu> To: ADSM-L@VM.MARIST.EDU Date: 02/17/2011 10:13 AM Subject: [ADSM-L] How many disk volumes are too many? Sent by: "ADSM: Dist Stor Manager" <ADSM-L@VM.MARIST.EDU> I am aware of the TSM design that says the more disk volumes you have, the more it will spread out the I/O for better performance. I also realize a lot of this doesn't really apply what with RAID-5, EMC SAN, multi-terabyte storage, etc. So, at what point does having lots of smaller volumes (for a disk LZ), not give you any more benefit, I/O wise? I have a 5.3TB SAN space on my new 6.2.2.0 server. Originally, I started formatting 200GB volumes then moved to 300GB, up to 25-volumes. Now I am adding another 5.3TB space and was wondering if I should continue with 300GB or jump to 500GB? Simultaneous sessions should not be an issue since most of these backups are Domino TDP and therefore single thread. I don't think there is a peak of more than 60-simultaneous sessions. The TSM server is a Dell T710 with 48GB RAM and 15K internal disk for the DB & Logs. Your thoughts? Zoltan Forray TSM Software & Hardware Administrator Virginia Commonwealth University UCC/Office of Technology Services zfor...@vcu.edu - 804-828-4807 Don't be a phishing victim - VCU and other reputable organizations will never use email to request that you reply with your password, social security number or confidential personal information. For more details visit http://infosecurity.vcu.edu/phishing.html U.S. BANCORP made the following annotations --------------------------------------------------------------------- Electronic Privacy Notice. This e-mail, and any attachments, contains information that is, or may be, covered by electronic communications privacy laws, and is also confidential and proprietary in nature. If you are not the intended recipient, please be advised that you are legally prohibited from retaining, using, copying, distributing, or otherwise disclosing this information in any manner. Instead, please reply to the sender that you have received this communication in error, and then immediately delete it. Thank you in advance for your cooperation. ---------------------------------------------------------------------