Help finding a Unix friendly RAID 1 backup


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# 29  
Old 03-31-2011
Quote:
No. Sorry I didn't realize this. You seemed confident the disk had USB connectivity and I didn't question it too deeply.
No worries. Well, I was confident the disk had USB connectivity; and it does, just not in the way I, or any normal person, need it. SmilieThat bit of info certainly could have been made clearer in the product specs; I read USB and saw a USB port and, incorrectly, assumed it would work.


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1) Return the Buffalo HD and purchase another HD that has proper USB connectivity.
That's what I'd do.
Thankfully, Amazon returns are easy enough.

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You'll never be able to do a bare-metal backup that way. It'll never recognize a network-only disk. Things on a network don't just appear because you plug them in (except for DHCP servers). It has to be used in other ways, and likely can't be done from a gentoo livecd since it's probably CIFS. Won't be trivial to do so on a full linux system, either. It won't be able to use it as a disk anyway, just as NAS.
And thus why I wasn't able to find any info online or in my book. Your answer provides the technical "why" and makes me feel a little better about the situation. Once again, your help has been invaluable.

It appears I may have a trip to best buy in my future if I want to get this done before the end of the week.

---------- Post updated at 12:28 PM ---------- Previous update was at 11:46 AM ----------

I have another question, that's really more of an option, but I'm interested in your opinion.

One of the reasons I am doing (as you suggested) a bare-metal backup is that, in the event the server hard drive fails, I can crack the hard drive open and replace it. If that is the case and I need to purchase something different anyway, would it be a good option to get an appropriate internal hard drive, with an enclosure that supports USB? Since it will only be used as a bare-metal backup to do at most weekly updates, is this acceptable? From what I understand, the external hard drives provide portability and cooling fans to help with prolonged and constant use. However, if I don't really need either of those and full replacement functionality is desired, is that a better option or am I simply making things more difficult for myself?

---------- Post updated at 12:57 PM ---------- Previous update was at 12:28 PM ----------

I realize that most of the larger external enclosures include fans anyway so that really isn't a differentiating factor. I understand buying a prepackaged external HD is easier; I just worry that, in the event of failure, it will be difficult to extract the HD and/or the HD won't be compatible with the system. (I've never cracked open a prepackaged external HD before.) Though, it occurs to me now that compatibility could be an issue regardless of whether the HD is external or internal without specifically knowing the hardware layout of the system.
# 30  
Old 03-31-2011
Quote:
Originally Posted by c.wakeman
I have another question, that's really more of an option, but I'm interested in your opinion.

One of the reasons I am doing (as you suggested) a bare-metal backup is that, in the event the server hard drive fails, I can crack the hard drive open and replace it.
Exactly. Even if it ended up being the wrong kind of drive, you could get a more appropriate drive and copy the bare-metal backup onto it.
Quote:
If that is the case and I need to purchase something different anyway, would it be a good option to get an appropriate internal hard drive, with an enclosure that supports USB? Since it will only be used as a bare-metal backup to do at most weekly updates, is this acceptable?
That should work quite fine.
Quote:
From what I understand, the external hard drives provide portability and cooling fans to help with prolonged and constant use. However, if I don't really need either of those and full replacement functionality is desired, is that a better option or am I simply making things more difficult for myself?
You can get USB SATA cradles which you pop SATA drives into like bread into a toaster(hence the name "hard drive toaster"), but if you're just going to have the same drive sitting in it all the time, a case would make more sense and look better(no exposed electronics when working, no carrying drives around in static baggies).
Quote:
I realize that most of the larger external enclosures include fans anyway so that really isn't a differentiating factor. I understand buying a prepackaged external HD is easier; I just worry that, in the event of failure, it will be difficult to extract the HD and/or the HD won't be compatible with the system. (I've never cracked open a prepackaged external HD before.)
You can't be 100% certain without opening your server's case, but given the size and age of the disk I think it's probably SATA. It's getting harder and harder to find old-fashioned wide cable ATA drives these days.

Look for a USB enclosure with a removable plate in the front for accommodating a CDROM drive, those are intended to be opened and will definitely have a standard disk in it. Little handheld USB hard drives will only have laptop-sized drives in them at best -- sometimes you get a weird disk that's not even laptop form-factor.

Don't get a drive that's only big "enough", get a drive that's plainly bigger than what the server has. You don't want to take a chance on an "identical" drive actually being smaller because of the different ways of measuring capacity(mebibytes vs megabytes).

Last edited by Corona688; 03-31-2011 at 02:07 PM..
# 31  
Old 05-17-2011
Corona68

I wanted to start by thanking you for all your help; I should have posted this sooner but, the backup worked and there doesn't seem to have been any ill effects.

I have not had time to explore a more permanent, robust solution due to work constraints but for the time being, people are happy with the backup. However, it is time to backup the server again using the same HD and since you were so helpful last time, I hoped you could provide some tips again.

Basically, how do I go about backing up the server so that only the files that have been added or altered since the last backup are transferred? I imagine this is preferable so the whole backup doesn't take 6+ hours. I know we have discussed this previously, but I couldn't find a definitive answer in your previous posts. Let me know if you need more details.

Again, thank you for your help.
# 32  
Old 05-17-2011
Glad it worked for you.

I needed to do some more research into rsync, I hadn't used it lately, but understand it a bit better now.

If you want to synchronize the contents of the two drives, I'd stick to just updating the /home/ partition, that seems to be where all the changing data is kept:
  1. Plug in the USB drive, and run fdisk -l to see what it shows up as. Your internal disk showed up as sda, so I suspect the external will show up as sdb, but best not to assume.
  2. Mount the external drive's home directory onto /mnt/external. To do this, mkdir -p /mnt/external ; mount /dev/sdb6 /mnt/external.
  3. Use rsync to copy new files to the drive. rsync --dry-run -r -a -H /home/ /mnt/external
  4. Optionally, if you want, use rsync to delete files from /mnt/external that no longer exist in /home/ rsync --dry-run -r --delete -a -H /home/ /mnt/external
  5. umount /mnt/external && sync wait for it to finish and then it will be safe for you to remove the USB drive, if you want to.
Note how I'm doing
Code:
rsync ... /path/ /path2

Having the exact right number of slashes is crucial.

Also, for the record, the various flags I'm giving it have these meanings:
Code:
-r    Recursively, so it checks folders in folders in folders
--dry-run    Only says what it's copying or deleting and doesn't actually do it!
                  Remove when you're confident it's copying what you want where you want.
--delete      Removes files not found in the source from the destination
-a               Preserves many things like ownership and timestamps
-H              Preserves hard links.  May not be necessary, and may improve performance to leave out.


Last edited by Corona688; 05-17-2011 at 12:14 PM..
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