Re: [Networker] Query in Staging from adv_file
2008-08-21 15:00:06
On Aug 21, 2008, at 2:39 PM, Curtis Preston wrote:
Francis Swasey said:
As currently implemented, you are correct. A stage or a clone or
multiple recovers may be performed on the AFTD. If a stage is
running,
clones and recovers have to wait for it to complete.
Hmmm... VTLs don't have that problem. ;) OK, they sort of do. You
can't restore from a tape that's currently being cloned, but you can
restore from other tapes. It looks like the entire AFTD is held up
while cloning/staging is going on.
Assuming you were using 10 GB virtual tapes (and I think you should),
this would cause a maximum of a 3 minute delay for a given restore if
you were using a VTL and you had tape contention. Here's my math: A
10
GB * 2:1 compression = a 20 GB tape. At a clone speed of 100 MB/s
(which you should easily get if you bought the right one), that tape
will be cloned/destaged in about 3 minutes, allowing it to be used
for a
waiting restore.
Another AFTD limitation that I've heard of, but haven't verified is
that
the RO side of the AFTD is counted in some way against your device
count. I don't know the details and haven't verified, but there are
some per server device limits that certain versions of NW have, and my
understanding is that the AFTD is counted as two against those
numbers.
Can anyone verify that this is true or false?
I don't think device count is relevant in a NetWorker environment
because EMC doesn't license anything based on device count. What I am
starting to see is that a VTL would be better for my environment
because it would be easier to carve out the storage space into lots of
little (10GB VTs) instead of having larger ADFTs. I figure that with
the law of large numbers on my side, the odds of needing to recover
data from lots of virtual tapes with them all staging is much slimmer
then my needing to recover data from far fewer, but larger ADFS
devices that are all busy staging data when I need to recover something.
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- Re: [Networker] Query in Staging from adv_file, (continued)
- Re: [Networker] Query in Staging from adv_file, X4500 experiences, Attila Mester
- Re: [Networker] Query in Staging from adv_file, X4500 experiences, Ronquillo, Merill C CIV NFELC, IT41
- Re: [Networker] Query in Staging from adv_file, Francis Swasey
- Re: [Networker] Query in Staging from adv_file, Curtis Preston
- Re: [Networker] Query in Staging from adv_file,
Stan Horwitz <=
- Re: [Networker] Query in Staging from adv_file, Terry Lemons
- Re: [Networker] Query in Staging from adv_file, Stan Horwitz
- Re: [Networker] Query in Staging from adv_file, Francis Swasey
- Re: [Networker] Query in Staging from adv_file, Curtis Preston
- Re: [Networker] Query in Staging from adv_file, Will Aymond
- Re: [Networker] Query in Staging from adv_file, Curtis Preston
- Re: [Networker] Query in Staging from adv_file, Bruce Breidall
- Re: [Networker] Query in Staging from adv_file, Curtis Preston
- Re: [Networker] Query in Staging from adv_file, Will Aymond
- Re: [Networker] Query in Staging from adv_file, Francis Swasey
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