Wanda, >From what I've read about DDP, it's not ideal for TSM workloads as it's at a performance penalty for large sequential operations compared to RAID6. This whitepaper from Dell (They license the same DDP technology) has some numbers and at a 256K transfer size, DDP is at a 63% read penalty compared to RAID6. That would have a big impact on backup performance to tape.
http://i.dell.com/sites/doccontent/shared-content/data-sheets/en/Documents/Dynamic_Disk_Pooling_Technical_Report.pdf Also, why use separate 'landing pools' for data rather than backing up to the dedup pool directly? So long as deduprequiresbackup is set to 'yes,' data in the pool will remain duplicated until offsiting to tape. Matthew McGeary Technical Specialist PotashCorp - Saskatoon 306.933.8921 From: "Prather, Wanda" <wanda.prat...@icfi.com> To: ADSM-L@VM.MARIST.EDU Date: 07/03/2014 03:09 PM Subject: Re: [ADSM-L] TSM 7.1 and dedup "chunking" issues Sent by: "ADSM: Dist Stor Manager" <ADSM-L@VM.MARIST.EDU> Well. That was certainly a surprise! Wonder what causes that - I've seen it happen to other people's posts before and always assumed they were using an off-brand mail client. But I wasn't doing anything differently than usual (MS outlook). Anyway, I had another question about your setup - I have a customer I manage with a similar setup, except the 200 clients are VMs generating about 4 TB of inc blocks daily. We also use a non-dedup landing pool, then back up to tape copy pool, then migrate to dedup pool. We are using devclass of DISK for the landing pool. It's a DS3500 with SATA disks, but is a DDP array, but is also in the same array as the dedup pool and the DB (We've requested SSD for the DB and should have it soon. The config is not ideal, but this is a leftover system which was originally configured to back up something else much less I/O intense.) Was thinking the backup stgpool might run faster if the landing pool is of type FILE instead of DISK. Don't know if it matters since it's a DDP array. What format is your landing pool, FILE or DISK? Wanda -----Original Message----- From: Bent Christensen [mailto:b...@cowi.dk] Sent: Thursday, July 03, 2014 3:32 AM To: Prather, Wanda Subject: RE: [ADSM-L] TSM 7.1 and dedup "chunking" issues Hi Wanda, The below is what got through of your response to "TSM 7.1 and dedup chunking issues" on the TSM list server :-) It is really a pain that you don't receive a copy of what you put up on the list :-) - Bent