Legacy HDS Forums

Shadow Image with external storage

Discussion created by Legacy HDS Forums on May 5, 2008
Latest reply on Jun 5, 2008 by Legacy HDS Forums

Originally posted by: stephen2615



Greetings,

I was wondering if anyone is using Shadow Image with lesser tiered external storage.  We have USP's with LDEV's that I would like to use Shadow Image to pair up on that I can present to other hosts.  Thats the easy part.  I just wonder about how the LDEV's on something like an externalised AMS system could cope with relatively heavy I/O especially if we were thinking about using SATA drives.

The USP uses 15k 146 GB FC disks.  If I was to pair up 500 GB SATA drives, is that going to work if the USP LDEV's are working relatively hard?  I believe there are options in the USP to cater for this so as not to completely muck up the cache but surely there must be something that pays. 

So, perhaps, it works like this?  The initial Shadow Image pair should be done during a relatively quite time.  Once the pair has been created, then any changes to the data are really only at the block level and a lot of the I/O such as reads don't actually affect the pairs.  Some of the True Copy resyncs are really outstanding compared to the size of the data.  So, I would summise the same thing happens with SI.  If I had the pair broken for only a fraction of the time, then the resync's should be ok?

Would anyone care to comment on this?

Stephen

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