Backup media choices for FreeBSD servers
jerrymc at msu.edu
Tue Apr 24 16:09:17 UTC 2007
On Mon, Apr 23, 2007 at 05:01:17PM -0700, L Goodwin wrote:
> I need to implement an automated backup facility on the FreeBSD file server I'm setting up for a client. It will have a software RAID 1 Mirror/Duplex that is made available to Windows XP SP2 and Windows Vista Home Premium users as a Samba share. I also plan to create system recovery disks (disk images) for the server and each Windows client.
> This leaves backing up user data on some schedule. I've read "Backup Basics", but have some questions:
> Which is best backup media for a FreeBSD file server, based on known issues (or lack of) with each format? I need to decide between the following formats:
> a) CD-R (or CD-RW?)
> b) DVD-R (or CD-RW?)
> c) Streaming tape (which format/standard?)
Generally, CD doesn't hold enough to be practical for any modern sizeable
file system. DVD is a little better, but still only a drop in
a many GB file system.
My suggestion is to use either tape or a large external hard drive.
Since you are mirroring, maybe the hard drive would be a good choice.
You will be less concerned about recovery of immediate errors than
about a systematic rotating archive. Buying about 5 large external
drives is currently cheaper than buying a quality tape system, although
handling the tapes can be easier and more flexible, plus easier to
deal with continuation media if you have a very large filesystem.
I would choose either LTO or DLT tape if you go that route.
The DDS (DAT) tape just is not robust enough to handle a real
server environment. It is OK for occasional copies to transfer
data somewhere or save something off - providing you check if the
tape is readable, but not hard core server backups.
But, I have had no problem with either DLT or LTO. They are fast
and reliable and have good capacity and can be set up so a dump
can span more than one unit if necessary. If you are running
a serious server, the increased cost will disappear in the the
increased reliability and usability.
I just noticed below that you indicated a 1GB backup that gradually
grows. (They always grow faster than expected). Well, DLT or LTO
would be overkill for that and also be very expensive. But it is
too big already to be practical for CD. Although DVD would currently
handle it, you would grow out of it soon. I think the large external
hard drive on USB might be your best bet for now - see more comments
> Which is the best method for backing up data files on a Samba sharer FreeBSD?
> Handbook says dump is the only way to go.
Dump is the way to go. It works well, is already on the system and
handles all types of files, links and permissions, ownerships, flags, etc
correctly. Almost every other system has something missing somewhere.
You can use dump regardless of which media you choose. There is no
prepreparation needed for tapes. If you use a large hard disk, then
you do need to fdisk, bsdlabel and newfs on it to create a file system.
Then you can write the dumps to an ordinary file on the filesystem you
create on the disk. If it is large enough you can write more than one
dump. You can just rm old/obsolete dumps without any other mucking
> Is it possible to have a Windows client perform the backup files on the Samba share to a local Re-Writable CD or DVD drive? If the answer is YES, what are the pros and cons of a UNIX-based (data-file only) backup vs. a Windows-based one?
> Please add to my list of pros and cons:
> Windows Backup:
> PRO: Backup can be restored to a Windows drive while server is being fixed?
> CON: Users might forget to replace backup disk after using optical drive.
Sounds like that would be a separate issue. Do an extra backup from the
Windows point of view if you want as some sort of interim support. But
backup the whole system of data via the UNIX/FreeBSD side. That will
allow you to put things completely back the way you want it most easily.
> FreeBSD Backup:
> PRO: Out of sight from users (server is in a storeroom).
> CON: Cannot restore backup to a Windows disk while server is being fixed?
> These are some of my other considerations:
> 1) Cost is a primary concern. Budget does not allow for a multi-drive solution. Best if client does not handle backups (change discs/tapes), so a solution that permits storing several backups to same disc/tape preferred.
Since extra high capacity hard drives are almost as cheap now as one or
two large DLT or LTO tapes (let alone the drives), that 'multi-drive'
solution may be your most economical method.
> 2) I only want to back up user data (not the OS). Current user data occupies less than 1GB of drive space, and is expected to grow at a modest rate.
Well, even a single extra large capacity USB hard drive will be less than
buying an extra DVD writable drive and give you room for a couple of
hundred 1GB size backups.
> 3) I do NOT have a writable CD or DVD drive (but can buy one if not too spendy).
> 4) I have an external SCSI connection, but very little "shelf" space.
> 5) The server does not have room for another internal device (except if swapping out the existing ATAPI CD-ROM drive).
> 6) I have an Ecrix Corporation Model VXI-1A SCSI internal tape drive that I assume is obsolete (comments appreciated). Anyway, I don't have room for it.
> 7) Have not yet settled on a backup schedule. May be weekly or monthly or ad-hoc, but daily is probably out of the question. The RAID 1 array is expected to provide some degree of protection in leieu of daily backups. Plan to back up all documents each time, rather than implement a two-tiered backup process.
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