At home my family has several computers connected to a wired (T100)
network. Since each of us produces a large amount of critical files
which we'd like to backup for an indefinite amount of time, as well as
to have some protection from unforeseen disasters such as a house
fire, we are considering setting up a RAID-1 on a special computer
dedicated for this purpose. This computer would be placed into a part
of the house so it can be better protected from fire, flood and other
disasters. Since a lot of data is personal, we really do not wish to
move the data over the network to somewhere outside of our property
(but would consider it -- our connection to the outside world is not
that fast, though.)
We envision this RAID-1 to run Windows 2000 Server.
2K server does fine, but Linux is free and will also do what you're
describing just fine. Go with one of the free alternatives and
use the thousand bucks or so you save on better hardware.
It will have three
IDE harddisks, two very large capacity disks for the RAID-1 disk
mirroring or duplexing, and the third disk to be a smaller one
sufficient to hold the OS.
Duplicate the OS disk, too, otherwise getting your data back is going to
be a major pain.
It will be a software RAID-1 system, since
the main purpose of this system is long-term storage only -- the
stored files will only be accessed on occasion so blazingly fast I/O
speed is not critical. This box will be run from a UPS with surge
protection. And it will be placed into an insulated brick/cement
enclosure in the basement so if a fire or whatever occurs, there is a
chance that at least the harddisks will survive (I'll be separately
researching how to buld this enclosure, but any recommendations you
have are welcome.)
Problem with the enclosure in the basement--in the event of fire where
do you think all the water the firemen pour on it is going to end
up? And immersion in dirty water is not good for disks either. You
could of course seal the enclosure but then you have cooling issues.
If you have a detached garage or other outbuilding with power, consider
putting a backup server there.
Now a couple questions:
1) Should I consider duplexing rather than mirroring (duplexing is
where each storage disk is run from its own controller -- mirroring
is where both disks run off the same controller). Will duplexing
even work in Win2KServer? (I'm essentially clueless on these
matters.)
This will work fine.
I prefer mirroring for now for cost reasons because it's the
integrity of the data, and not whether it is available 24-7, which
is the most critical. Of course, with mirroring I worry about the
situation when the single controller goes on the fritz and that it
damages the data on *both* harddisks. Or don't controllers damage
harddisk data when they go bad?
The situation you describe can occur, but there is another
consideration--with typical PC IDE controllers, the channels are not
well isolated, so a drive failure on one channel can corrupt data on a
drive on the other channel. Adding a completely separate controller
should address this.
2) What inexpensive, high capacity IDE drives (brand/make) should I
consider? I'm thinking in the 100 gig to 250 gig size. Which ones
are reputed to be more reliable than average? I don't necessarily
need high speed disks, just work horses. Anyway, the I/O of the
system will probably be limited by the home network speed, so I
really don't need to worry about high-speed harddisks, SCSI,
hardware raid, etc.
Pick any drive and somebody somewhere is going to tell you how he saw 90
out of a hundred of them fail. Provide clean power and adequate cooling
and any current drive should run for years.
Any other insights you can give on this issue, including web sites
which discuss how to do what I want to do, are more than welcome.
Thanks.
Bud
(p.s., a third question. What are my options for temporary media
backup of the RAID-1 system? Something that will handle 25 Gigs or
more? Or is that prohibitive in cost? I'm thinking I may wish to
periodically backup what's on the RAID-1 harddisks onto some media for
storage in a fire-proof safe or maybe even off-property somewhere.
This adds to the level of security of the data. Very critical data is
now being backed up on CD-ROM and kept in a small fire-proof safe, but
this is now getting to be unwieldy since the quantity of data is many
gigabytes now, and when I start digitizing family pictures and such,
will become a substantial fraction of a terabyte.)
Just a suggestion, but get a high-performance hardware RAID controller
such as the ones that 3ware sells, and set up a 3 drive raid with
hot-sparing and use removable drive trays. Put three drives in,
designate one a spare, and go. When you're ready, pull one of the two
active drives and put it in the safe deposit box or whatever and the
remaining drive will automatically be mirrored onto the spare. Then
when you're ready to swap again, just repeat the process, putting the
drive you removed back in and designating it the spare.
Simplest way to archive up to 5 gig these days is DVD+/-R. There are
those who say it's not stable, and if you're talking about something
that has to last over geological time they're right, but for ordinary
purposes it's fine. Above 5 gig you can go with tape or with drives
in trays. Hard disks don't cost a whole heck of a lot more than tape
cartridges with equivalent capacity these days, so which you go with is
more a matter of philosophy than anything else.
