Re: [Networker] Turning off indexing on pools - need advice?
2008-07-21 11:44:03
George Sinclair wrote:
If you have indexing turned on for a given pool, and you later turn it
off, will this affect your ability to use nwrecover to recover data that
was backed up prior to turning it off? Can this setting be turned on and
off without affecting the information that was added to the index when
it was last on?
I wouldn't think so as this just determines whether or not the index is
updated on the server's disk, so the information would still be there,
assuming of course that you were still within the browse policy, but any
new data backed up to the pool would not be reflected in the index, so
this could only be recovered via save set recover. But if the feature is
then re-enabled later then subsequent backups will again add information
to the index. That right?
The reason I ask is because I have a special pool for very specific
one-time level full data sets, and I currently have indexing enabled for
the pool (the group, too, for that matter). I enabled indexing because I
wanted to be able to do a few browsable recovers to test that the data
was backed up correctly. The first and only save set written thus far is
1.7 TB, so that's a lot of data to read through to do a save set
recover. I also made temporary clones, but my plan is to recycle those
clone volumes once the originals are off site. The clones were only
created to further ensure that the originals could be read OK. In this
regard, perhaps the indexing is moot, but seemed useful.
Unfortunately, these backups are one-time. There will be no further
backups of these save sets at any level. As a result, the information in
the index may never expire or get removed if there's never any more
backups, right? If that's the case, the index might grow bigger than I'd
like, so it might start to eat into available disk space. As a result,
it might be necessary to turn off indexing on the pool if I start to
notice appreciable disk shortage following subsequent backups to this
pool. I do have a *limited* number of save sets that will be backed up
to this pool (maybe 15 more at 1 TB or so each?), and then I'm done, but
not sure how much the index will grow as a result, and I'm thinking that
with no later backups, that space might just sit there and never get
truncated or freed up.
The particular NSR client resource that writes to this pool has a browse
policy of 6months and a retention policy of a Decade. There are other
NSR client resources for this same client that are members of other
groups and write to other pools, so it's not as if this is the only
client resource that updates the index.
I really don't need to keep the index entries around forever, but I
would like to be able to have the capability to perform a browsable
recovery at some point in the future. The only way I know to do that,
assuming the entries are no longer still on disk, would be to recover an
older backup of that index, but that's not possible if indexing is
turned off on the pool. But if it's turned on then I might end up eating
into more disk space than I want. Seems I'm damed if I do, damned if I
don't. Any advice?
Very long question with a short answer.
* With indexing turned on at time of backup: index is written for that
save set. Browse and retention for that save set is set at the time of
the backup.
* Pre-existing save sets are not affected by this setting.
* An index for a save set can easily be removed using "nsrmm -o
recoverable -S 123456789". You can trim down the indices for any
particular save set in this way. The index can be replaced later by
nsrck -L7 or by scanning.
* A save set that was written without indexing on can never become
browsable unless you scan it. No other way.
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