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SCSI Unmap (thin reclaim) with SRDF
Hi all,
Just received a query on how the unmap works in an SRDF environment where the host only sees the R1 box.
I expect that unmap will be intercepted on the R1 side and run there, but how does it get to the R2 side?
Will this also be handled as a VAAI or will these be all single commands between the R1 and the R2 device?
Thanks in advance,
Patrick
rawstorage
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December 11th, 2014 01:00
The following paper discusses all the use case in detail for unmap.
http://www.emc.com/collateral/hardware/white-papers/h8115-vmware-vstorage-vmax-wp.pdf
SRDF will do the unmap on the remote device. See page 47 for explanation of how this works in SRDF/A and S
UMNAP to a thin SRDF is accepted and supported on the R1 and is propagated to the remote replicas (R21, R2) as long as the links are active and the remote boxes are also running a minimum of enginuity 5876.159.102
Neel_c
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December 10th, 2014 22:00
I am not sure but i dont think you can unmap a R1 devices if the srdf is not SPLIT before hand.
Once you split the 2 devices then only you can go ahead and unmap them.
Hoping for someone with more knowledge to confirm what actually happens
Patje
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December 11th, 2014 03:00
Great, thanks!