I also use shadow files, but unlike Fish, I do (occasionally) merge them.? I usually do this once per year.? I think that Fish doesn't have the same issue that arises when you apply maintenance to the system, so keeping a single base at one level does make sense for him.? But, if you apply monthly or quarterly RSU maintenance, then you will end up with a greater number of shadow files over time.? I'm not sure what the limit on shadow files is now, but it was 8 when I set up my standard backup routine.? Obviously, if you apply maintenance and each maintenance set is a separate Shadow file, you will reach the limit fairly quickly.?
The "safest" (according to IBM) sequence to apply the RSU maintenance to z/OS, and the one IBM likes, is to get the hiper stuff on asap and apply the maintenance at the quarterly RSU releases, which for 2024 will be (RSU2403, RSU2406 RSU2409 and RSU2412).? So even if you were to just use that method, you wouldn't get very far before you were at the limit.?
Some people don't apply maintenance at all, and some simply load the new levels that are released periodically, which is likely the case for Fish, so his method works for him.? It just doesn't work for me, but then everyone does things differently so what works for me or for Fish, might not work for you.?
I have found that merging the shadow files down to just one shadow is quite simple.? Merging into the base file is where you have to really worry and I have had a couple times (my fault) where it failed.? My solution (which Fish? probably won't like) is that when necessary (or yearly at the longest) I merge to just the one shadow, and then using DASDCOPY64 copy the Base and the single shadow and make a new base.? That gives me the new BASE that I want, plus leaves me with the backup of the old base and shadow file(s).
I also copy everything every day and my backups are not just the Hercules data, but everything on my computer.? I have five 4TB NVMe drives (20TB total) and a 20TB HDD.? I don't use all of the space on the NVMe drives, they actually run at around a single TB (more or less) on each one, and I use a program called BVCKUP2 (very inexpensive and very good) to make very quick copies of everything to alternate NVMe drives.? NVMe to NVMe especially with BVCKUP2 which can be set to copy only the changed blocks within each file, and not the entire file, is extremely quick (a matter of seconds).? Then everything also gets copied to the 20TB HDD (in the background and only from the backup copies not the original data on the NVMe drives).? I also make daily copies of some drives with Acronis to the HDD in incremental format.? Weekly the HDD gets copied to my NAS (4 20TB drives).? I also take a weekly (full every 16 weeks) and incremental (every week) of the NVMe drives directly to the NAS.? I have a duplicate, though slightly smaller NAS at another location that is used to hold snapshot copies of my primary NAS. ??
So, for me, space is not really an issue, but recovery is.? If I could have more than 8 shadow files (I rarely go above 4), then I would/might change things a little, but it would probably be less efficient to have more than 8 and that's likely why they set that limit.
I'm not saying that you should go out and buy a bunch of hardware, but based on the way I use Hercules, the way I do things works for me.? I'm constantly moving between RSU levels and sometimes before certain hipers, and my way lets me move to just about any maintenance level of any year back for several years.? Most people don't have a need to do that, but I do.? In my case, when the NVMe drives went on a super good sale, (4TB Western Digital Black drives for right around $125 each) so I bought a bunch, the same with the 20TB Seagate Ironwolf Pro drives (which were also cheap at about $150 each) and the NAS boxes that ended up costing more than the DASD inside of them.?
Brian
