I agree that RAID-5 is not good for TSM( DB,LOG or Stg pool voulmes). Basic reason is poor performance. But I can't find any literature to back the statement up. I'm having trouble convincing the IT architects....need hard facts..any ideas?
Zlatko Krastev/ACIT wrote: > 2. There definitely is a reason NOT to use RAID-5 for TSM. If you want > your TSM server to snake like a worm put DB and Log on RAID-5, especially > with a big stripe size - one of the best methods to shoot yourself in the > leg. RAID-5 for diskpool volumes also will have performance impact but not > so disastrous. It seems like you have enough disks to use mirroring or > RAID-1 so why not. > I still prefer to use raw LVs instead of filesystems despite the fact > community on this list cannot completely agree is there any significant > benefit or penalty for doing so. Using 'mklv -t tsm_db', '-t tsm_log' and > '-t tsm_vol' fairly well describes what those LVs are for and I am not > forced to exclude the files for the client on the server itself. IMO raw > LVs are few percent faster than JFS files, there is no need to worry about > large-enabled filesystems and file I/O buffering does not consume the > memory TSM server can use better. > > 1. 8x 9GB after mirroring will give you 36 GB. It looks to be enough for > both DB and Log. If your DB is not under 27 GB (cannot fit in three disks, > you wrote <30) and you cannot afford 9-th and 10-th disk (DB and Log on > separate disks gives best performance) you will be forced to use same > disks for DB+Log. Create 1-1.5 GB LV in the center of each disk for Log. > Create one or two LVs on the same disks for DB. It is recommended to > mirror them through TSM but you can also use AIX mirroring or RAID-1. > > 3. For both DB and diskpool volumes it is better to have one (IMO) volume > per disk. Other people on this list suggest more than one but opinions are > consolidated that more than few will have negative impact on performance. > Disk head moves will prevale disk reads/writes and performance will > suffer. > > Zlatko Krastev > IT Consultant > > "Varney, Patrick" <[EMAIL PROTECTED]> > Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED]> > 30.09.2002 22:21 > Please respond to "ADSM: Dist Stor Manager" > > To: [EMAIL PROTECTED] > cc: > Subject: TSM Database Disk Layout Recommendations > > Hello All, > > I'm sure that this general question has been asked many times, but every > situation is different. And I can't seem to get to the www.adsm.org site, > so > here goes. > > We just received some new SSA disks for our TSM servers and I'm looking > for > some advice on the best way to lay everything out. Here are the details on > our planned environment (the SSA configuration has not been done yet, so > it's flexible): > > Server: > RS/6000 7026-H70 > 4-way processor > 4GB memory > 1 SSA HBA (2 loops) > AIX 4.3.3 ML 10 > TSM 4.2.2.12 > Internal SCSI Storage: > 4 x 9GB (current TSM database/log location) > SSA Loop 1: > 8 x 9GB > RAID 5 > Approx. 60GB > SSA Loop 2: > 8 x 72GB > RAID 5 > Approx. 500GB > TSM Database: Less than 30GB > TSM Log: 3-4GB > Disk Storage Pools: 300GB > > My current plan is to put the TSM database on the 9GB SSA drives (using > RAID > 5, no TSM mirroring), the disk storage pool volumes on the 72GB SSA > drives, > and use the internal 9GB drives for database dumps to disk. However, I'm > open to suggestion. Specifically, I am looking for answers to the > following: > > - Where is the best place for the TSM database log volumes? And if they > are > sharing space on the SSA disks, is there any advantage to creating a > separate file system (in general, is there any performance > advantage/disadvantage to multiple file systems on one SSA RAID array)? > - Is there any reason to NOT do RAID 5 on the SSA disks? > - For the database and disk storage volumes, is it better to create more > smaller (2GB) volumes or enable "large file" support and create fewer? > > Any help would be greatly appreciated. > > Thanks, > > Patrick Varney > Pacific Gas & Electric Company > Fairfield Information Operations Center (FFIOC) > Enterprise Services Group (ESG), Senior Network Specialist > * internal 8-227-2823 > * external 707-436-2823 > * pager 707-288-1513
