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John Jolet wrote: |
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> |
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> On Jan 24, 2006, at 9:10 PM, Ow Mun Heng wrote: |
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> |
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>> On Tue, 2006-01-24 at 17:23 +0000, Francesco Riosa wrote: |
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>> |
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>>> Jeff wrote: |
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>>> |
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>>>> Hey guys. |
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>>>> |
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>>>> I've got this big fat backup server with no space left on the hard |
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>>>> drive |
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>>>> to store a tar file. I'd like to pipe a tar through ssh, but not sure |
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>>>> what the command would be. Something to the effect of: |
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>>>> |
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>>>> # cat /var/backup | ssh backup.homelan.com 'tar data.info.gz' |
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>>>> |
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>>>> So that, the data is actually being sent over ssh, and then |
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>>>> archived on |
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>>>> the destination machine. |
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>>>> |
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>>> tar -zcf - /var/backup | ssh backup.homelan.com "( cat > |
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>>> data.info.gz )" |
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>>> |
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>> |
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>> There's another way. This assumes your originating server's CPU is |
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>> slow/precious and you have a 16 way node on a backup server (HAHA!!) |
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>> |
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>> tar cf - /var/backup | ssh backup.homelan.com "gzip -c > |
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>> filename.tar.gz" |
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>> |
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>> But you transfer the stream uncompressed, so more bits get transferred. |
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>> |
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> you're kidding, right? Unless you've got a PII on the originating |
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> end and are using gigabit ethernet between the two nodes, compressing |
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> the data before transmission will almost always be faster. I tested |
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> this scenerio extensively about 3 years ago, using linux, aix, and |
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> solaris hosts. In no case was transferring uncompressed data faster |
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> than compressing (at least to some degree) the data on the |
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> originating server. And frankly, no matter what you do...wouldn't |
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> you hope ALL the bits get transferred? :) |
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I read something some time ago that suggested if you transfer a |
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compressed file over a compressed SFTP connection, for example, that it |
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would take longer to transfer the data versus if only the data or the |
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connection was compressed. The reason, as I recall, had to do with |
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compressing already compressed data--this apparently created some |
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overhead on the connection. |
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|
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Did you look at this situation in your tests? If so, what were the results? |
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-- |
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