On 4/18/07, Bill Sprouse <[EMAIL PROTECTED]> wrote:
It seems that neither Legato nor NetBackup seem to lend themselves well to the
notion of lots of file systems within storage pools from an administration
perspective. Is there a preferred methodology for doing traditional backups to
tape from ZFS where there are hundreds or thousands of filesystems? Is there a
disk-to-disk-to-tape method? Sorry for the murky question.
It is a good question.
I asked this over a year ago and the result was an RFE whose number I
lost. Initially I wanted a way to do a dump to tape like ufsdump. I
don't know if this makes sense anymore because the tape market is
crashing slowly. People just don't backup 300MB per night anymore. We
are looking at terabytes of data and I don't know how to backup a
terabyte a night. I don't even know how the big banks are going to
address the data explosion that shows no signs of slowing.
I recall, back in 1997, I was at camp Microsoft out in Seattle where I
was given a full tour of the facility and got to meet with Jeff Raikes
and a stack of techies. Top notch world class techies and we were
looking at Microsoft Exchange and its database backend or lack
thereof. I simply refused to buy the idea that it was a "zero
administration" system at the time. That was a buzzword back then. The
other issue on the table was backup. I recall being quite adamant that
any system must be able to be backed up in a fashion that allows the
state of a system or software set to be restored precisely at some
point later in time. I was stunned at the time to learn that there
were some 4 terabytes of data in all those compaq racks that MS had
and no way to do a backup. At all. To me, at the time, that was just
bad engineering. Perhaps I was myopic and could not see what the ZFS
designers can plainly see; there are no backups anymore.
So now here we are ten years later with a new filesystem and I have no
way to back it up in such a fashion that I can restore it perfectly. I
can take snapshots. I can do a strange send and receive but the
process is not stable From zfs (1M) we see :
The format of the stream is evolving. No backwards compati-
bility is guaranteed. You may not be able to receive your
streams on future versions of ZFS.
This leaves us with tar or cpio or Joerg Schillings star. But if you
have many man file systems and they are larger than a LTO tape ( or
whatever media du jour ) then you will need to figure out a way to do
the backups. Somehow.
If there were *ever* a discussion that needs to happen then it
certainly is the state of backups with ZFS.
How shall we begin ?
Maybe with a definition of what a "backup" is and then some way to
achieve it. As far as I know the only real backup is one that can be
tossed into a vault and locked away for seven years. Or any arbitrary
amount of time within in reason. Like a decade or a century. But
perhaps a backup today will have as much meaning as papertape over
time.
Can we discuss this with a few objectives ? Like define "backup" and
then describe mechanisms that may achieve one? Or a really big
question that I guess I have to ask, do we even care anymore?
Dennis
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