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TDAT HYPERS
Can anyone explain what the relationship betwean a TDAT and a physical drive is? My understanding is that a physical drive allocated to a thin pool is split into several Tdats.
also how is the raid spread amongst same drive types in a pool? If I have allocated the recommended 8 drives to a existing 6+2 RG in a thin pool do these drives stay as their own small group of 8 drives I.e less of a spindle spread.
TIA
echolaughmk
522 Posts
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May 20th, 2015 17:00
Hi,
TDATs stand for Data Devices. These are the "hypers/splits" that are created on the physical drives in the BIN file with the data_device attribute. These data devices are then put into a Thin Pool and are used as the backing physical devices for all TDEVs bound to that Thin Pool.
The Data Devices (TDATs) are created with the desired RAID protection and the physical spindles that comprise the Data Devices are grouped into disk groups in the BIN. If you have 16 physical spindles in a disk group and you create Data Devices on them with RAID6+2 and then allocate all of those Data Devices to the same Thin Pool, your pool will be comprised of (2) RAID6+2 raid groups at the physical layer.
Here is a visual representation that might help (a little old from my collection but might help show some of it):
jcalero1
7 Posts
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May 21st, 2015 00:00
thanks for a clear answer, none of the docs I had read broke down what an actual TDAT comprised of they just referred to them. That was a a great visual you provided, is it part of a article or doc I could read?
thanks again
echolaughmk
522 Posts
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May 21st, 2015 10:00
Hi,
That picture was pretty much it. It was created manually when we used to be in the field working for EMC as an aid to help visualize the new changes in the VMAX so it doesn't exist in any document published by EMC to my knowledge. The best document I have seen with somewhat similar images to explain it is this one:
https://support.emc.com/docu7383_Best-Practices-for-Fast,-Simple,-Capacity-Allocation-with-EMC-Symmetrix-Virtual-Provisioning.pdf?language=en_US
Glad this helped!
-K