Financial System... No Tape. Tear Me Apart.

Discussion in 'OT Technology' started by Peyomp, Dec 30, 2006.

  1. Peyomp

    Peyomp New Member

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    I'm thinking of going without a tape backup, for a financial system. I know some of you are adamant about tape, so I would appreciate you telling me what an asshat I am, so I can consider my options.

    We use clustered MySQL on two redundant Sun DB servers running ZFS, with two redundant management nodes. Data is fed to these systems by redundant protocol servers.

    I am thinking of running a small server to run a replicated MySQL database in ARCHIVE mode, which means it is still queryable, read only, but doesn't take much space. The server would be mirrored ZFS, and if possible we would also mirror off site. That is not always possible.

    We'll have about a terabyte of data, tops. I looked at tape systems, and anything over 300GB is very expensive.

    Thoughts?
     
  2. deusexaethera

    deusexaethera OT Supporter

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    What are you going to do if the office burns down? It's easy for the CFO to toss a backup tape in his briefcase every Friday afternoon and take it home to lock in a safe -- it's not easy to synchronize a terabyte of data over any reasonably-priced internet connection.
     
  3. Peyomp

    Peyomp New Member

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    Replicating the data off site is easy over DSL, because it builds slowly to that level, and then you just xmit the new data, compressed. It may or may not be easy in this case for someone to take a tape home, but thats a good point for instances where off-site replication is not possible. Some sites allow a VPN out, some will not.
     
  4. Peyomp

    Peyomp New Member

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    Single tape LTO-3 systems look like they can be had for $5000. Hmmm... more like $12K with platinum hardware support.
     
  5. Doc Brown

    Doc Brown Don't make me make you my hobby

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    I don't know shit about this, but isn't tape backup a bit slow?

    Why not use hot swappable hard drives?

    I mean, if 1tb is the most you're dealing with...
     
  6. Peyomp

    Peyomp New Member

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    Each database server has redundant power supplies and RAID-Z doing striping with parity over several disks, can detect errors as they happen, and can operate one disk down. Whats more, the application keeps going if one database or management server fails.

    We're talking about backup in addition to these two servers, which each has redundant components.
     
  7. EvilSS

    EvilSS New Member

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    "Hot Site" replication is a great choice for disaster recovery, but what happens when you find out 8 days after the fact that some critical data in the database was corrupted* and needs to be reverted to it's previous values?

    The nice thing about tape is that you not only have a copy of the current data (or close to it) but you also have copies of past data. In most cases you are more likely to need old data for some reason than to need to completely restore due to a total loss of the system. Of course, you could easily do snapshot backups to disk, just be sure you are covered in case of a) hardware failure and b) site failure (burned down, aliens blow it up, sucked into a black hole, etc).

    *Edit: and by corrupted I mean made incorrect, usually by human or program error. Not disk corruption or something like that.
     
  8. Peyomp

    Peyomp New Member

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    Yes, and for this reason it is preferable to ship log files off site, and applying them on a timed delay. You can do this with Max DB. I don't know yet if you can do it with MySQL.

    We also have the option of doing ZFS snapshots for this purpose.
     
  9. Doc Brown

    Doc Brown Don't make me make you my hobby

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    I understand that, but it's still just redundant backup.

    Backups of backups of backups.

    But then again, like I said. I don't know shit about this stuff.:wiggle:
     
  10. deusexaethera

    deusexaethera OT Supporter

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    Emmet: tape is very slow at random access, but it's just as fast at sequential access as disks are -- and they have a much higher data density than disks, as a result of being a 3-dimensional recording medium. (Note that a reel of tape is much, much thicker than the microns-thick coating on disk platters.)

    Peyomp: If you're absolutely dead-set against using tape, you could use a realtime data stream to protect against physical damage AND a nightly incremental table dump to a second drive to protect against human error. You'd have to have extra space to store the incremental table dumps, but if you can afford one terabyte, you can afford two terabytes.
     
    Last edited: Dec 30, 2006
  11. Doc Brown

    Doc Brown Don't make me make you my hobby

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    "I did not know that"

    <Johnny Carson voice>
     

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