I'm in the 'belt - suspenders (braces) - safety pins - glue - duct tape' crowd myself. I have my TSM database on a fiber-attached ESS; TSM mirrors this to the same ESS in a different logical subsystem (ran out of money -- couldn't get the second ESS). The TSM logs are also mirrored on the same ESS to yet another pair of subsystems.
I've never noticed anything in the way of a performance issue -- but my database is only using 71% of 20 GB. Tom Kauffman NIBCO, Inc -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Paul Fielding Sent: Friday, April 08, 2005 1:54 PM To: ADSM-L@VM.MARIST.EDU Subject: Re: Question on SETUP I'd be interested to know if anyone has done real performance testing re: using TSM mirroring with a RAIDed backend. People on the list are raising valid reasons for using TSM mirroring on top of RAIDed disk (though I think that it's important for people to understand exactly *why* they are doing this and ensure that they've laid out the disk they're using appropriately - eg. mirroring to a bunch of files in the same FS is probably a bad idea). The next question though, would be what sort of performance hit might one take in doing this? Obviously not a simple question as there are factors such as whether or not the disk being mirrored is same type, is the mirrored data going out the same scsi/fc wire, etc. That being said, if those factors are considered and mostly mitigated, do people find anything else in this scenario that might cause a performance hit, or do things seem to fly along quite nicely? regards, Paul ----- Original Message ----- From: "Prather, Wanda" <[EMAIL PROTECTED]> To: <ADSM-L@VM.MARIST.EDU> Sent: Friday, April 08, 2005 12:21 PM Subject: Re: [ADSM-L] Question on SETUP > Yet another opinion: > > If you are running TSM HSM, that requires 24x7 availability. Then you > should mirror both DB and logs. > > If you are NOT running TSM HSM, a lot of TSM installations can actually > afford to have TSM down a couple of hours. > SO what I usually do, when I have the DB on a RAID device, is just to > mirror the recovery log. > > That way, if you DO lose the DB due to some type of logical corruption, > you can always restore from your last DB backup, and roll forward from > the log. So you lose no data, just some time. > > It's adequate protection, if you can afford the time. > > (That assumes you run in ROLLFORWARD mode, which you SHOULD be doing, > and you are very religious about your DB backups, which you SHOULD be!) > > > > > > > -----Original Message----- > From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of > Joerg Pohlmann > Sent: Thursday, April 07, 2005 10:38 PM > To: ADSM-L@VM.MARIST.EDU > Subject: Re: Question on SETUP > > > Hi Paul. From bitter experience I have been saved by TSM mirroring on > nicely protected disks. I have had complete filesystems clobbered as > result of other hardware failures, nothing to do with the disks - have > had > filesystems damaged on AIX and also Windows. TSM mirroring is such a > superb, inexpensive protection against these other failures that I > always > recommend TSM mirroring. It's also quite inexpensive give todays cost of > disk storage, including Shark. And yes, on a Shark I would create four > filesystems (/tsmdb1 /tsmdb2 /tsmlog1 /tsmlog2 - Windows an D: E: F: and > G: drive) so that the 1s and 2s (or the E: and G: drive) are in > different > LSSs. > > And yes, I wear belt and suspenders. > > Joerg Pohlmann > 604-535-0452 > > > > > Paul Fielding <[EMAIL PROTECTED]> > Sent by: "ADSM: Dist Stor Manager" <ADSM-L@VM.MARIST.EDU> > 2005-04-06 23:25 > Please respond to > "ADSM: Dist Stor Manager" > > > To > ADSM-L@VM.MARIST.EDU > cc > > Subject > Re: Question on SETUP > > > > > > > I don't see the value in mirroring the db and logs if they're placed on > Shark disk. The purpose of TSM's mirroring is to provide disk > redundancy > in case of disk failure. However, the Shark provides it for you. Why > add > the extra overhead of software mirroring when the hardware does a > valiant > job in the background. The Quck Start recommendation doesn't take into > account that your disk is already protected... > > regards, > > Paul > > ----- Original Message ----- > From: "Jones, Eric J" <[EMAIL PROTECTED]> > To: <ADSM-L@VM.MARIST.EDU> > Sent: Wednesday, April 06, 2005 2:56 PM > Subject: [ADSM-L] Question on SETUP > > >> Good Afternoon. >> I was asked to setup a new TSM server 5.2.2 on a AIX 5.2 server. >> My question has to do with setting up the DB, LOG and DISKPOOL. >> On our current servers which run the same O/S and TSM version the DB, > LOG >> and DISKPOOL are mirrored. >> On the new system I'm setting up these are all going to reside on a > IBM >> SAN(SHARK) which is all RAID. >> Is there any reason to mirror them since the mirror would be on the > same >> set of drives(space was already allocated on a LUN)? >> I understand it's always good to mirror(protect DB, LOG, DISKPOOL) but > in >> this case I'd have to mirror to the same set of disk since I was only >> allocated a set of space to work. In the TSM class it also > recommended >> that you mirror for protection. >> I'm in the middle of reading the "Quick Start" for the second time and > I >> see they recommend "Mirror your Database and recovery log for "Server > and >> storage pool protection". I wanted to make sure there was not a >> performance issue or anything else. >> >> Have a Great Day, >> Eric Jones >>> * [EMAIL PROTECTED] >>> *: 607-751-4133 >> Cell : 607-972-7621 >> >
