Re: ADVFS and fragmentation.
From: bofh00 (jnielsen_at_aero-graphics.com)
Date: 08/04/03
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Date: Mon, 04 Aug 2003 08:19:02 -0600
On Sat, 02 Aug 2003 01:23:15 +0000, Jack Patteeuw wrote:
> So you have **ONE** AdvFS domain that is 800 GB ?!!
>
> How do you back that up, or don't you ? In the event of a failure of
> the RA8000, do you know how many **DAYS** it would to restore this
> amount of data ? Putting all of your eggs in one basket (domain) is
> asking for a disaster. (We recently has a RAID failure (different
> hardware and OS) and it took 3 days to rebuild ! SH*T happens !!)
>
> My first suggestion is to split the data into 4 domains. With enough
> CPU's you should be able to defrag those 4 over a weekend.
>
> jp
Yes it is one domain.
Yes we do back it up after I debated the issue for well over a year
with management.
I would say average backup time is about 18 hours which will improve
at some point since the backup system will be connected via a
dedicate GB line (currently only 100baseTx-FD). Obviously the time
it takes to back up is dependant upon the amount of data. I have seen
it take near 24 hours when there is approximately 760GB on the system.
It is backed up to a cheap IDE->SCSI raid5 on a remote system using
Bakbone Netvault software once per week. Yes, once per week. Pretty
crazy/stupid? *nod* All know the consequences. Hell could be worse
it could be the days when we had no backup and when I preached about
it I was just talking to brick walls. About half the data is in
some form replicated. For example the pyramid files I spoke of are created
from the TIFFs. Beacuse of this the most critical things to backup
are the tiffs in that situation and NOT the pyramids. Pyramid
generation is time consuming but not considered a major issue.
Basically to make a long story short they were willing to lose a
week of work if the system were to fail.
I have actually seen this raid fail but it was not hardware. There
was an issue apparently with ADVFS and the file table system
was corrupted. I worked with Compaq techs for nearly a week on
it.
I have also rebuilt this raid before and if I recall correctly (it
has been well over a year quite possibly two) it only took me a
matter of hours from scratch to get the raid up and running and then
a restore overnight. I have also had to restore about 600GB to the
system and it didnt even take a day to do so.
Ideally we would have this system raid1+0 or 0+1 along with a local
backup system setup to backup at least critical data. But Ill tell
you what...
You convince my boss to pay what it costs to do all of this the
"right way" and Ill be VERY grateful. Somehow though I suspect you
will have even less luck than I. They would not even fund a backup
system until we lost approximately 200GB of data.
With regard to using multiple domains I am not sure I follow you
as to why multiple ones would be better? Ill be the first to admit
that not only do I not know jack about ADVFS but Im also a novice
with regard to these systems. But how would using multiple domains
make any differnce in restore or recovery times? 800BG is 800GB.
Would it not actually take longer to rebuild multiple domains and
perform multiple restores in part due to interruption than a single
one? Also would we not also be forced to use seperate mounts for
each domain? Having multiple mounts is out of the question. It is
not even an option.
BTW, just to be clear it is 4 raid5 volumes (hardware side 6 drives
per volume) that compose a single advfs domain. Not one 24 drive
raid5 and one advfs domain.
Anyhow, I am open to any suggestions for better setup etc and
appreciate them
Thanks.
- Next message: bofh00: "Re: ADVFS and fragmentation."
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- In reply to: Jack Patteeuw: "Re: ADVFS and fragmentation."
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