Hallo Zlatko, both the originator and me wrote about disastreous performance with stripping raid-10. You write about read-before write penalty with raid-5. I do not understand?
regards Juraj > -----Original Message----- > From: Zlatko Krastev [mailto:[EMAIL PROTECTED]] > Sent: Monday, August 19, 2002 2:37 AM > To: [EMAIL PROTECTED] > Subject: Re: diskpool performance > > > It depends on how the RAID controller implemented RAID-10 (or > RAID-1E). If > your write request is small (and random as in TSM DB) you can > easily hit > read-before-write penalty usually found in RAID-5. > > Zlatko Krastev > IT Consultant > > > > > Please respond to "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> > Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> > To: [EMAIL PROTECTED] > cc: > > Subject: Re: diskpool performance > > Hey, > > what the hell was your raid-10 like? > Raid10 is by no means slower than raid1, if correctly > implemented (by the > means of the raid controller). > I had it previously on an ICP-Vortex controller, and it was > real blessing. > > But there are another curiosities as well - I see > worse performance on IBM Raid Controllers using Raid-1E (raid > 1 consisting > of more than 2 disks) > compared to Raid-1. > More spindles, less performance, .. makes no sense as well.. > > > regards > Juraj Salak > > -----Original Message----- > From: Roger Deschner [mailto:[EMAIL PROTECTED]] > Sent: Wednesday, July 31, 2002 3:54 AM > To: [EMAIL PROTECTED] > Subject: Re: diskpool performance > > > The disk storage pools need to be RAID-1+. It's "other people's data" > and you are responsible for it, from the moment it is backed up from > their client systems. As you have discovered, performance is not good > with anything other than RAID-1. > > The Database and the Log also need to be RAID-1. (Mirrored by > TSM or the > OS or something) I tried striping (RAID-10, in effect) my TSM > database, > and caused a performance disaster that I had to back out of fast. The > Log might survive RAID-5 without any performance penalty; I haven't > tried it. Just remember that the Log is strictly write-only until > disaster recovery becomes necessary. > > Roger Deschner University of Illinois at Chicago > [EMAIL PROTECTED] > > > On Sun, 28 Jul 2002, Seay, Paul wrote: > > >There is one caveat Mark. > > > >If the loss of a backup is a critical failure to an > application, then you > >must Raid-1 or Raid-5 the pool. I have applications that > take processing > >cycle backups several times throughout their processing > cycle. I also > have > >servers that have to have the same backup cycle. So, an unprotected > >diskpool is not a black or white answer to solving a > performance problem. > > > >However, you are correct, RAID-5 is going to perform like > crap for disk > >pools unless you have ESS disk which have a very large disk > cache on the > >front and the RAID-5 turns into RAID-3 (no reads before > writes because it > is > >always a full stripe write). > > > >Paul D. Seay, Jr. > >Technical Specialist > >Naptheon Inc. > >757-688-8180 > > > > > >-----Original Message----- > >From: Mark Stapleton [mailto:[EMAIL PROTECTED]] > >Sent: Sunday, July 28, 2002 1:46 AM > >To: [EMAIL PROTECTED] > >Subject: Re: diskpool performance > > > > > >From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED]]On Behalf Of Dirk >Kastens >> Seemed to be a faulty raid controller. We always used raid5 for TSM >> volumes and never got any errors or bottlenecks. Of course, we use >> different raids for stgpools and the database. > >A question: why are RAIDing your TSM diskpool? There's no need for >redundancy in the diskpool, since the diskpool is not the mission-critical >component of your backup system. It's the *tape* pool you need redundancy >for, and that's what a copy pool is for. > >You *might* RAID 0 your diskpool, so that you stripe across the pool disks >for a larger number of read/write heads, but there's nothing but unnecessary >overhead when you RAID 5 it. The diskpool dies? You fix the pool, and you >back up the files again the next night. > >-- >Mark Stapleton ([EMAIL PROTECTED]) >Certified TSM consultant >Certified AIX system engineer >MCSE >