Topic: Using RAID1 or rsync to backup

[ryan]

It is my understanding that any attempt to backup to a disk or share will result in a 2g or 4g limitation. If more than 4g of data exists, there is a problem.

Does RAID1 "run" the server on drive hda? My idea is to install the backup harddrives into inexpensive removable caddies like this:

http://www.compgeeks.com/details.asp?invtid=GN210

Get a server running with RAID1. To backup, simply shut down the server and swap the removable drive (hdb) with a 3rd identical drive. Restart SME. Would RAID1 then boot from hda, and regenerate the newly inserted hdb? This would allow one of the 3 drives to be kept off site. If hda ever failed, SME should continue to run off hdb using RAID1. If the server was stolen or destroyed, the harddrive kept off site could be used in a similar computer without having to restore. Would this work? I don't understand the technicals regarding RAID1 so I hope someone has input to share.

My second thought does not use RAID1.  The other idea I had is to mount hdb and use rsync to copy the entire hda to hdb every night.  Can rsync copy files that are open or in use?  How about an open database?  If the backup drives in the caddies are duplicate drives, they may even be hot swapable.  Any input is appreciated.

Purchasing caddies and 2 extra hard drives is much cheaper than a tape drive and several media cartridges.

RS

[69GM]

Mitel has REALLY BAD instructions on how to resync a software RAID drive.

But I suppose it could be done...

http://www.e-smith.org/docs/howto/RAID-recovery-howto.html

[ryan]

69GM,

Thanks for the lead.  It does appear to be a lot of work just to handle a backup.  Maybe the rsync idea to a removeable hard drive is better....as long as rsync can copy open files and databases.

Thanks

ryan

[Rich Lafferty]

Nothing will be able to reliably copy open files and databases, because the
byte that makes the file useful might be the one that comes right after
you've read it. It's a fact of life of backups that files being written won't
be backed up (which is why you run your backups in off hours and keep
more than one day's backup around).

As for databases, that's what mysqldump is for -- never rely on copying live
tables. Take a look at the existing backup events to see what we do, and do
that to disk instead of to tape.

Cheers,

--Rich

[rob]

or implement a hotswap raid such as http://myezserver.com/mrs-raid.html

We use an accusys version here in N.Z. but if you live in Canada the MRS is a good device.

[Tom Keiser]

I've done (and been burned by) some of this, and offer the following suggestions:

1. You can use a 3ware card, and use their 3DM management software to remove a synced drive, then install and rebuild the raid drive replacement. If you do, be sure and use a top quality removeable drive cage (not the Genica your URL points to) and also use e-smith 4.1.2 where there are native 3ware drivers and software. You will have to compile drivers for SME =>5, and they probably will give you fits.

2. Darrell May's MRS unit is also a good choice. Both it and the 3ware units are smart enough to back up open files, if left installed for a while.

3. Have more than one spare -- that is your only backup! I'd buy at least 8 drives and carriers, preferrably something like the RJR100 from StorCase. It's going to still cost you less than a DDS4 DAT drive and tapes, and you'll have a real backup, perhaps of 60GB or 120, etc.

4. If you use the MRS unit, be very careful when installing hard drives that have any open circuitry on the bottom, as the drive will almost be touching the metal tray. It won't take much to create a short that will keep the MRS running, but prevent it from backing up. I found one today that had been used every week, but had last backed up on June 19th, because of a short.

After running this hard drive backup arrangement for several months, I believe it is practical, but I would also copy the *VERY* important files to another HDD nightly, using something like Copycat 3.0. see: http://www.hahntech.com/  You simply can't have *TOO* much protection.

Hope this helps.

Tom Keiser

rob wrote:
>
> or implement a hotswap raid such as
> http://myezserver.com/mrs-raid.html
>
> We use an accusys version here in N.Z. but if you live in
> Canada the MRS is a good device.