[gpfsug-discuss] Online data migration tool

[Simon Thompson (IT Research Support)]

I agree that migration is not easy.

We thought we might be able to accomplish it using SOBAR, but the block size has to match in the old and new file-systems. In fact mmfsd asserts if you try. I had a PMR open on this and was told SoBAR can only be used to restore to the same block size and they aren't going to fix it. (Seriously how many people using SOBAR for DR are likely to be able to restore to identical hardware?).

Second we thought maybe AFM would help, but we use IFS and child dependent filesets and we can't replicate the structure in the AFM cache.

Given there is no other supported way of moving data or converting file-systems, like you we are stuck with significant disruption when we want to replace some aging hardware next year.

Simon
________________________________________
From: gpfsug-discuss-bounces at spectrumscale.org [gpfsug-discuss-bounces at spectrumscale.org] on behalf of aaron.knister at gmail.com [aaron.knister at gmail.com]
Sent: 26 November 2017 18:00
To: gpfsug-discuss at spectrumscale.org
Subject: [gpfsug-discuss] Online data migration tool

With the release of Scale 5.0 it’s no secret that some of the performance features of 5.0 require a new disk format and existing filesystems cannot be migrated in place to get these features.

There’s also an issue for long time customers who have had scale since before the 4.1 days where filesystems crested prior to I think 4.1 are not 4K aligned and thus cannot use 4K sector LUNs to hold metadata. At some point we’re not going to be able to buy storage that’s not got 4K sectors.

In both situations IBM has hamstrung its customer base with large filesystems by requiring them to undergo extremely disruptive and expensive filesystem migrations to either keep using their filesystem with new hardware or take advantage of new features. The expensive part comes from having to purchase new storage hardware in order migrate the data.

My question is this— I know filesystem migration tools are complicated (I believe that’s why customers purchase support) but why on earth are there no migration tools for these features? How are customers supposed to take the product seriously as a platform for long term storage when IBM is so willing to break the on disk format and leave customers stuck unable to replacing aging storage hardware or leverage new features? What message does this send to customers who have had the product on site for over a decade? There is at least one open RFE on this issue and has been for some time that has seen no movement. That speaks volumes.

Frankly I’m a little tired of bringing problems to the mailing list, being told to open RFEs then having the RFEs denied or just sit there stagnant.

-Aaron
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