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June 11th, 2018 08:00
IBMi Backups/Sizing and DD6300
Based on sizing recommendations of our IBMi backups (BRMS) we implemented a DD6300 with 2 ES30 shelves (45T) mid-year 2017. After almost a year’s time we are at 72% capacity and concerned that we’ll either need to expand our current DD or begin copying our historical data back to physical tape.
Basic Backup Information:
Backup Type Size Retention
Weekly Backup Full 15T 2 Year
Daily Incremental 9T 5 Week
Archives Archives 2T Retention varies from 2 years-Indefinite
We have seen growth in our backups since the original sizing estimates were provided. However, those estimates gauged less than 20T DD in the first year with an annual growth estimate of 5%. We are instead seeing an average monthly storage increase around 5% on the DD.
Below is a recent snapshot of our DD size and compression rates:
- Single VTL pool 2000 LTO5 volumes 1.5TB. 900 scratch volumes currently available.
- DD replication to DR site (Source 72% full/Target 71% full)
Is what we're seeing for de-dupe rate/compression average? Recommendations/advice to improve in an IBMi backup environment?
rugby01
85 Posts
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June 11th, 2018 10:00
A couple notes:
VTL's are like real tape - unless you erase/reuse them - they NEVER release the storage associated to them
.
So number one:
You should only have enough scratch tapes fill up every drive, and to hold what you need (plus maybe 2 cycles overhead for growth). What is happening here is your just eating new tapes and never releasing the blocks on old tapes. You must overwrite the old tape to get blocks back. We see this all the time that users just create 3000 tapes, and never re-use the first tape until tape 3000 is full.
So to fix this - you need to calculate how many tapes per day you need, multiple by days retention, and then add a couple weeks. You need to destroy all the tapes that have been used and expired, and then run cleaning.
This should reduce your usage massively.
Kevin
akdavis1
2 Posts
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June 14th, 2018 10:00
Thank you for the response. We are cycling our tape inventory and re-initializing tapes via BRMS as they expire. With our retention periods we are usually only gaining a little over 1TB of cleanable space per week.
As I understand it once the 'tapes' are initialized it creates cleanable space on the DD which is reclaimed during the weekly cleaning cycle.