Hey George,
I do pass a list of ssids to nsrclone, but since that list contains all valid
ssids on each volume I want to clone in practice it actually clones the whole
volume. nsrclone is smart enough to take the list of ssids and backup them up
one volume at a time as opposed to sequentially backing up one ssid at a time.
I don't use the clone volume feature because I want to be able to exclude
non-valid ssids(incomplete,suspect). I suppose the "per volume" might do this
automatically... but this way I know for certain I'm not getting any junk data
on my clone tapes.
FYI I also send my original and now "verified" tapes offsite. So any online
restores come from the cloned media. This process verifies my offsite media,
and to a degree does a "random" verify on my cloned data.
Joel
-----Original Message-----
From: George Sinclair [mailto:George.Sinclair AT noaa DOT gov]
Sent: Monday, April 21, 2003 10:04 AM
To: Legato NetWorker discussion; Joel Fisher
Subject: Re: [Networker] Merits of cloning versus dual backups?
We found that out when someone attempted a recover. We did not have the
blocking set correctly, or rather NetWorker was not using variable block
size and was instead defaulting to some other default size. What this
caused was two things. First, it took NetWorker a long time to reach the
correct part of the tape since positioning by record was disabled due to
the wrong block size and second, recovery of the data itself was very
slow, and I'm thinking it much slower than it should have been, so I
suspect that the wrong blocking size may have also contributed to slower
recover times once NetWorker did find the start of the data. Anyway, we
resolved the problem, but in our case, we learned the easy way, too,
since we didn't operate like that for to long before fixing the problem.
I have a question, though, where you say "I clone full volumes". How
then, or maybe I should ask why would you pass it a list of ssids? Are
you in fact generating a list of ssids and the nusing some kind of
script to process each one? If so, is it working through the list one at
a time? Why not just use the clone volume feature so you don't have to
generate the list?
Thanks.
George
Joel Fisher wrote:
>
> Not sure if I missed this point in the thread, but as long as you're cloning
> all or most of the ssids on a volume you should get nearly maximum drive
> speed on cloning. My cloning runs anywhere between 20-80Mbs, because I clone
> full volumes(or all !incomplete,!suspect ssids). From what I see it doesn't
> do any de-multiplexing, it just reads data from list of ssids you passed to
> it and writes it in the same order.
>
> I started full scale cloning just about 2 months ago and it has already saved
> my butt. It turned out we had a firmware issue with our drives, but I never
> got any errors until we attempted to read the data. Now, because of the
> cloning we are attempting to read every single saveset we back up so I
> started seeing a bunch of media errors. After a couple of weeks of trouble
> shooting we wound up putting the latest firmware on the drives, now all is
> well. Moral of the story is... if I hadn't been cloning I wouldn't have
> known I wasn't getting good backups until someone needed a restore. Not a
> good time to find that out.
>
> Joel
>
> -----Original Message-----
> From: Teresa Biehler [mailto:tpbsys AT RIT DOT EDU]
> Sent: Friday, April 18, 2003 3:45 PM
> To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
> Subject: Re: [Networker] Merits of cloning versus dual backups?
>
> Cloning verifies that the original copy is good, but not that the clone
> is. So, which copy do you send off site? Do you send the original
> because you know that copy is verified?
>
> -Teresa
>
> Terry Lemons wrote:
> >
> > AMEN to that. In fact, I used cloning for two purposes:
> > o create a second copy for offsite storage
> > o validate that the original copy is good
> >
> > In my experience, there is no other way to accomplish that second goal,
> > except by cloning.
> >
> > tl
> >
> > Terry Lemons
> > > CLARiiON Applications Integration Engineering
> > EMC²
> > where information lives
> >
> > 4400 Computer Drive, MS D239
> > Westboro MA 01580
> > Phone: 508 898 7312
> > Email: Lemons_Terry AT emc DOT com
> >
> > -----Original Message-----
> > From: Wood, R A (Bob) [mailto:WoodR AT CHEVRONTEXACO DOT COM]
> > Sent: Thursday, April 17, 2003 10:04 AM
> > To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
> > Subject: Re: [Networker] Merits of cloning versus dual backups?
> >
> > The thing to note is, when you make a clone, you are validating the
> > original backup. This could be priceless.
> >
> > Bob
> >
> > --
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