Hello, Some information I've got from TSM support that can be good to know about
DIRMC don't need to be configured to back up directories to a (separate) disk storage pool DIRMC specifies the management class (MC) for directories to bind to. If not specified, by default, the MC class in the active policy set of the policy domain with the longest retention period will be used for directories. If more than one MC with the same long retention period is configured, the highest in alphabetical order will be used. It is recommended that you select a MC for individual directories that retains directories at least as long as it retains the files associated with them. Restore order with TSM versions before Version 3 1997, two steps 1. Restore directories 2. Restore files DIRMC had a big impact on restore performance Best practice - > Advantageous to have directory information cached on disk to prevent from Unwanted tape mounts Unwanted tape locates Restore order with TSM versions after TSM Versions 3 and newer Restore order changed: Single step restore, files and directories Two step directory processing: 1. Create directories with default attributes. Directory information coming from the stored file object 2. Correct attributes and ACLs once data is read from tape DIRMC effects on transaction processing Transactions are used to create server aggregates, groups of logical files an aggregate represents 1 server physical file Multiple client logical files Transaction options TXNGROUPMAX (server, default 256) TXNBYTELIMIT (client, default 25600) Transactions allow improved server performance during server internal data movement operatons, e.g. Migration, backup storage pool etc. What happens during backup? If the client detects a change in the destination for the object to back up: End the current transaction independent of TXNGROUPMAX TXNBYTELIMIT Begin a new transaction Back up the object with reset transaction boundaries. In most cases the next object will be a file object again, so the current directory transaction will be ended and a new transaction will be started for the file objects. The directory will be send to the server as a single object within a transaction.This results in less objects being aggregated than expected Although the DIRMC is no longer required to optimize the directory restore stage it is still usefull: By default, directories are bound to the management class in the active policy set of your policy domain with the longest retention period and then highest in alphabetical order, which could point to a storage pool on tape unexpected mounts during restore unexpected time to locate the directory objects on tape To take maximum advantage of transaction boundaries and optimize server internal data movement operations, bind the directories to a MC with the same destination as the MC of the file objects, e.g. bind the directories to the same MC as the file objects (best practice). It is not required or recommended to have the DIRMC bind to a MC with a separate disk storage pool destination ____________________________________________ Kind Regards Mikael Lindström IBM Svenska AB SE-164 92 Stockholm, Sweden Visiting address: Oddegatan 5, Kista Mob: +46 70793 5096 E-mail: mikael.lindst...@se.ibm.com Prepared by IBM Attorney - IBM Confidential (Unless indicated otherwise) Christian Svensson <christian.svens...@cristie.se> Sent by: "ADSM: Dist Stor Manager" <ADSM-L@VM.MARIST.EDU> 2009-01-22 11:21 Please respond to "ADSM: Dist Stor Manager" <ADSM-L@VM.MARIST.EDU> To ADSM-L@VM.MARIST.EDU cc Subject [ADSM-L] SV: DIRMC Hi, DIRMC option could help you a lot depend on how you configure it. Make sure you configure DIRMC to save it's data on Disk only. Best Regards Christian Svensson Cell: +46-70-325 1577 E-mail: christian.svens...@cristie.se Skype: cristie.christian.svensson ________________________________________ Från: ADSM: Dist Stor Manager [ads...@vm.marist.edu] för ashish sharma [ashishsharm...@gmail.com] Skickat: den 22 januari 2009 06:31 Till: ADSM-L@VM.MARIST.EDU Ämne: DIRMC Hello, How could DIRMC option on server side improve the restore time.Any idea? -- Best Regards Ashish Sharma ST Microelectronics Ltd. 919717003853 Såvida annat inte anges ovan: / Unless stated otherwise above: IBM Svenska AB Organisationsnummer: 556026-6883 Adress: 164 92 Stockholm