Re: [WinMac] Need advice on a backup solution
Curtis Wilcox(cwcx[at]mail.rochester.edu)
Fri, 07 Jan 2000 16:48:52 -0500
While I think tape backup is the better way to go, I'm going to play
Devil's Advocate.
At 12:38 PM 01/07/2000 -0500, Tim Scoff wrote:
> There are a couple of reasons to go with a tape drive instead of a
>hard drive for backups.
>
>1. You may need to go back to a backup that is months old. A tape drive
>allows you to archive multiple versions of data for long periods of time.
>A hard drive solution allows you to archive data for one or two days only.
>I have seen people have to redo work becuase they overwrote their backup
>every day instead of rotating backups over an extended period when they
>deleted data on Monday and then tried to get it back on Friday.
There's nothing inherently wrong with choosing a backup mechanism which is
meant strictly for recovering from a failed drive on the server. In that
case you only need a backup older than your last system change (in case you
want to go back to the previous configuration). If that choice is made,
every client must know that the backup system won't pull their ass out of
the fire if they realize they overwrite the wrong file last week.
>2. Computers crash. If your server crashes while you're in the middle of a
>backup and you're backing up to a hard drive you may have just lost
>everything, both the server's hard drive and the backup. With a tape drive
>you still have the previous night's backup.
You could still do that with hard drive if you have more than one.
Just for fun, I'm going to imagine a backup system that uses hard drives.
I'm using local vendor J&N Computer Services as a reference and rounding up.
$ 700 PC (this one http://www.jncs.com/fpages/system.htm, but with a full
tower case instead of a desktop case)
$ 50 Promise Ultra66 PCI Controller
$1476 4 34GB IBM Ultra66 drives (the PC has its own disk for the C: drive)
$2196 TOTAL
This machine is only booted for the duration of the backup which greatly
extends its life. One disk holds a monthly backup, one a weekly and the
remaining two alternate nightly. If you've got the necessary network &
bandwidth, the PC itself could be located off-site. Anyway, a DDS-4 or AIT
tape drive is cheaper and more trustworthy but probably slower at backing
up and restoring.
>3. Off site data storage is easy with tapes. It's difficult with a hard
>drive.
True, and it's rare for insurance to truly indemnify a business which loses
data in a fire, flood, etc. Frequently that data is truly irreplaceable.
> I don't consider $4000 a bad price for a tape backup solution. I
>consider less than $2000 a mistake for important data, and no one takes the
>time to back up anything that isn't important.
> My suggestion would be to go with a tape autoloader so that you can
>have multiple tapes in the drive and change tapes once a week. You can
>also do incremental or differential backups with a full backup one day a
>week which can help reduce the amount of data that you need to back up
>every night.
If you choose a media size which you know will accommodate your needs for
the next few years, an autoloader can be substituted with a conscientious
employee swapping tapes on the assigned schedule. Autoloading adds a lot to
the price.
The data amount in this example is 15GB minimum. Lets assume for now the
maximum isn't too much higher than that. Looking in my APS catalog, I see a
DDS-4 drive w/ Retrospect for ~$1250. DDS-4 tapes are 20GB native, roughly
40GB compressed. As long as the bulk of the data is not graphics or other
uncompressible data, a whole backup could fit on a single tape. The media
is less than $40 so you could buy a lot of tapes and still be well under
$2000. Note that I have not included the cost of Retrospect client licenses
because it appears that they already have the licenses in this case.
The straight AIT holds 35GB/70GB and costs only $1900 so I'm not sure why
an AIT II drive (which holds 50GB/100GB) is necessary in this case. The AIT
II costs twice as much. The DLT drive holds a little more than the AIT and
costs about the same. I don't know what the advantages are of either DLT or
AIT tho'.
> Ask your director how important his data and his time is. Point out
>to him that if he goes with a backup solution that isn't reliable and his
>hard drive crashes he will have to redo all of his work. Now magnify that
>time investment in the data which you're backing up every night by everyone
>in the department and how much it will cost his budget in time to have all
>of the data that you are backing up recreated from scratch if the backup
>isn't good enough. At that price $4000 is cheap.
I know it can be hard, you have 20 computers and you're talking about
spending what it would cost to buy 3 more, but the risk is high enough and
the cost if you lost stuff is great enough that it is worth it. Again, from
the original message I'm not sure why the AIT II vs. AIT is needed but you
know best what capacity you need. If you're doing overnight backups the
additional speed shouldn't be an issue.
--
Curtis Wilcox cwcx@ats.rochester.edu
Desktop Systems Consultant 716/274-1160
Eastman School of Music Pager: x12-3290
While I think tape backup is the better way to go, I'm going to play
Devil's Advocate.
At 12:38 PM 01/07/2000 -0500, Tim Scoff wrote:
There are a couple of
reasons to go with a tape drive instead of a
hard drive for backups.
1. You may need to go back to a backup that is months old. A tape
drive
allows you to archive multiple versions of data for long periods of
time.
A hard drive solution allows you to archive data for one or two days
only.
I have seen people have to redo work becuase they overwrote their
backup
every day instead of rotating backups over an extended period when
they
deleted data on Monday and then tried to get it back on
Friday.
There's nothing inherently wrong with choosing a backup mechanism which
is meant strictly for recovering from a failed drive on the server. In
that case you only need a backup older than your last system change (in
case you want to go back to the previous configuration). If that choice
is made, every client must know that the backup system won't pull their
ass out of the fire if they realize they overwrite the wrong file last
week.
2. Computers crash. If your server
crashes while you're in the middle of a
backup and you're backing up to a hard drive you may have just lost
everything, both the server's hard drive and the backup. With a
tape drive
you still have the previous night's backup.
You could still do that with hard drive if you have more than one.
Just for fun, I'm going to imagine a backup system that uses hard drives.
I'm using local vendor J&N Computer Services as a reference and
rounding up.
$ 700 PC (this one
http://www.jncs.com/fpages/system.htm,
but with a full tower case instead of a desktop case)
$ 50 Promise Ultra66 PCI Controller
$1476 4 34GB IBM Ultra66 drives (the PC has its own disk for the C:
drive)
$2196 TOTAL
This machine is only booted for the duration of the backup which greatly
extends its life. One disk holds a monthly backup, one a weekly and the
remaining two alternate nightly. If you've got the necessary network
& bandwidth, the PC itself could be located off-site. Anyway, a DDS-4
or AIT tape drive is cheaper and more trustworthy but probably slower at
backing up and restoring.
3. Off site data storage is easy with
tapes. It's difficult with a hard
drive.
True, and it's rare for insurance to truly indemnify a business which
loses data in a fire, flood, etc. Frequently that data is truly
irreplaceable.
I don't consider
$4000 a bad price for a tape backup solution. I
consider less than $2000 a mistake for important data, and no one takes
the
time to back up anything that isn't important.
My suggestion would be to go with a tape
autoloader so that you can
have multiple tapes in the drive and change tapes once a week. You
can
also do incremental or differential backups with a full backup one day
a
week which can help reduce the amount of data that you need to back
up
every night.
If you choose a media size which you know will accommodate your needs for
the next few years, an autoloader can be substituted with a conscientious
employee swapping tapes on the assigned schedule. Autoloading adds a lot
to the price.
The data amount in this example is 15GB minimum. Lets assume for now the
maximum isn't too much higher than that. Looking in my APS catalog, I see
a DDS-4 drive w/ Retrospect for ~$1250. DDS-4 tapes are 20GB native,
roughly 40GB compressed. As long as the bulk of the data is not graphics
or other uncompressible data, a whole backup could fit on a single tape.
The media is less than $40 so you could buy a lot of tapes and still be
well under $2000. Note that I have not included the cost of Retrospect
client licenses because it appears that they already have the licenses in
this case.
The straight AIT holds 35GB/70GB and costs only $1900 so I'm not sure why
an AIT II drive (which holds 50GB/100GB) is necessary in this case. The
AIT II costs twice as much. The DLT drive holds a little more than the
AIT and costs about the same. I don't know what the advantages are of
either DLT or AIT tho'.
Ask your director how
important his data and his time is. Point out
to him that if he goes with a backup solution that isn't reliable and
his
hard drive crashes he will have to redo all of his work. Now
magnify that
time investment in the data which you're backing up every night by
everyone
in the department and how much it will cost his budget in time to have
all
of the data that you are backing up recreated from scratch if the
backup
isn't good enough. At that price $4000 is cheap.
I know it can be hard, you have 20 computers and you're talking about
spending what it would cost to buy 3 more, but the risk is high enough
and the cost if you lost stuff is great enough that it is worth it.
Again, from the original message I'm not sure why the AIT II vs. AIT is
needed but you know best what capacity you need. If you're doing
overnight backups the additional speed shouldn't be an issue.
--
Curtis Wilcox
cwcx@ats.rochester.edu
Desktop Systems Consultant
716/274-1160
Eastman School of Music Pager:
x12-3290
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