on AIX more LUNs/hdisks is better. There are some resources allocated per hdisk, where you want more. Set up 4 or 8 VG's for database. Growing database filesystems is easier than adding more.
Op 15 jul. 2015, om 16:23 heeft David Bronder <david-bron...@uiowa.edu> het volgende geschreven: > Same number of LUNs in fewer VGs, or fewer LUNs, too? The queuing concern > makes it sound like fewer LUNs. If so, as Rick says, that's also where your > I/O concurrency would suffer. > > If it's the same number of LUNs, using one VG per LUN makes it easier to > isolate each LV to each PV rather than potentially mixing them all together, > possibly having multiple LVs share the same PV, which could result in > database I/O to different DB2 volumes hitting the same PV and causing extra > contention. (To be fair, in modern SAN arrays, the consumer host has no idea > where any of the blocks really live in the back end, so that kind of > contention can and probably often does happen anyway.) > > My gut reaction with DB2 on TSM 6 and up is that nothing with the database > layout is as easily fixed as it was with the embedded database in TSM 5 and > earlier... :-/ There's always trade-offs... > > =Dave > > > On 07/15/2015 09:15 AM, Rhodes, Richard L. wrote: >> The concurrency I'm aware of is at the hdisk/lun level. There's a >> num_cmd_elems at on the fcs adapter which we set to 2k, and then queue_depth >> on the hdisk. That's why spreading I/O across as many hdisks/luns as >> possible is advantageous. >> >> Rick >> >> >> >> -----Original Message----- >> From: ADSM: Dist Stor Manager [mailto:ADSM-L@VM.MARIST.EDU] On Behalf Of >> Huebner, Andy >> Sent: Wednesday, July 15, 2015 9:33 AM >> To: ADSM-L@VM.MARIST.EDU >> Subject: Re: Disk layout for AIX >> >> He claims there is a queuing issue with too many at the HBA. I guess I >> missed that the last 12 years of being a storage/TSM admin. >> I told him the theory of using many was to allow more concurrency. Before >> we build I just want make sure this is not a mistake that cannot be easily >> fixed. >> >> Thanks, >> >> Andy Huebner >> >> -----Original Message----- >> From: ADSM: Dist Stor Manager [mailto:ADSM-L@VM.MARIST.EDU] On Behalf Of >> David Ehresman >> Sent: Wednesday, July 15, 2015 8:12 AM >> To: ADSM-L@VM.MARIST.EDU >> Subject: Re: [ADSM-L] Disk layout for AIX >> >> VGs are cheap. Why does your AIX admin want to reduce the number of VGs? >> >> David Ehresman >> >> -----Original Message----- >> From: ADSM: Dist Stor Manager [mailto:ADSM-L@VM.MARIST.EDU] On Behalf Of >> Huebner, Andy >> Sent: Wednesday, July 15, 2015 9:03 AM >> To: ADSM-L@VM.MARIST.EDU >> Subject: [ADSM-L] Disk layout for AIX >> >> I have an AIX admin that wants to build my new TSM server using two VGs for >> the database (6 file systems) and one VG for the various logs. >> We currently have 6 VGs for the DB and 3 VGs for the logs. Each VG contains >> 1 file system. >> >> The DB is about 375GB and the new hardware is a P8. >> >> No TSM de-dup. >> >> Should I be concerned about the DB setup? >> >> >> Andy Huebner >> > > -- > Hello World. David Bronder - Systems Architect > Segmentation Fault ITS-EI, Univ. of Iowa > Core dumped, disk trashed, quota filled, soda warm. david-bron...@uiowa.edu -- Met vriendelijke groeten/Kind Regards, Remco Post r.p...@plcs.nl +31 6 248 21 622