Discussion:
DFHSM and Large zFS files and DR
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Lizette Koehler
2017-09-06 14:15:20 UTC
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I am looking for some guidance on how to manage large (1TB or more) zFS Files.

When DFHSM does a backup it will use DFDSS to do the work. This quiesces the
zFS until the backup completes. This can cause the zFS to be unavailable for a
long time (30 mins or more) while the quiesce is waiting to complete or the
backup is in progress. If DFHSM cannot quiesce the zFS then there is no backup

Do most shops let DFHSM do backups on zFS files?
Do you have a limit of what size zFS DFHSM is allowed to do the backup?
Do you have a window when you allow DFHSM to do such backups?
How do you create a copy of a large zFS for Business Continuity or DR?


Thanks

Lizette Koehler
statistics: A precise and logical method for stating a half-truth inaccurately

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van der Grijn, Bart , B
2017-09-06 14:26:19 UTC
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I believe you can use flash copy (or similar). I looked at it a couple of releases ago (we're now z/OS 2.1) and at the time you could not restore a backup using FC to a new name. Seeing that the typical request is to restore individual files in the file system and not the whole file system, this was not a workable solution for us at the time. It's on my list to re-visit.

At the moment we use a home-grown, PAX bases, rexx, that probably won't work well for the size you're looking at.

Our DR relies on disk mirroring, which includes the zFS volumes.

Bart

-----Original Message-----
From: IBM Mainframe Discussion List [mailto:IBM-***@LISTSERV.UA.EDU] On Behalf Of Lizette Koehler
Sent: Wednesday, September 06, 2017 10:17 AM
To: IBM-***@LISTSERV.UA.EDU
Subject: DFHSM and Large zFS files and DR

List

I am looking for some guidance on how to manage large (1TB or more) zFS Files.

When DFHSM does a backup it will use DFDSS to do the work. This quiesces the
zFS until the backup completes. This can cause the zFS to be unavailable for a
long time (30 mins or more) while the quiesce is waiting to complete or the
backup is in progress. If DFHSM cannot quiesce the zFS then there is no backup

Do most shops let DFHSM do backups on zFS files?
Do you have a limit of what size zFS DFHSM is allowed to do the backup?
Do you have a window when you allow DFHSM to do such backups?
How do you create a copy of a large zFS for Business Continuity or DR?


Thanks

Lizette Koehler
statistics: A precise and logical method for stating a half-truth inaccurately
with the message: INFO IBM-MAIN

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John McKown
2017-09-06 14:38:49 UTC
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Post by Lizette Koehler
List
I am looking for some guidance on how to manage large (1TB or more) zFS Files.
When DFHSM does a backup it will use DFDSS to do the work. This quiesces the
zFS until the backup completes. This can cause the zFS to be unavailable for a
long time (30 mins or more) while the quiesce is waiting to complete or the
backup is in progress. If DFHSM cannot quiesce the zFS then there is no backup
Do most shops let DFHSM do backups on zFS files?
​We don't.
Post by Lizette Koehler
Do you have a limit of what size zFS DFHSM is allowed to do the backup?
Do you have a window when you allow DFHSM to do such backups?
How do you create a copy of a large zFS for Business Continuity or DR?
​We simply do a series of full volume back ups. This does not quiesce the
​filesystem. So the backup could be "fuzzy". However, this is done on a
Sunday when our activity is minimal.
Post by Lizette Koehler
Thanks
​I am wondering if you really need such a big zFS filesystem. Of course, if
you have really large files, then it most likely does need to be large. But
if you have multiple directories, I would simply find the larger ones and
split them off into their own zFS filesystem datasets. You could then back
them up. Since that could be done in parallel, your outage time should be
less.​
Post by Lizette Koehler
Lizette Koehler
statistics: A precise and logical method for stating a half-truth inaccurately
--
UNIX was not designed to stop you from doing stupid things, because that
would also stop you from doing clever things. -- Doug Gwyn

Maranatha! <><
John McKown

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