optimized configuration

[shutdowng0]

I have got a server with
12/24 cpus
48 GB RAM
110 TB Raid 6 Disk (/dev/sda)

and created a vdo store with

vdo create --force --vdoCpuThreads=12 --name=vdo1 --device=/dev/sda --writePolicy=async --vdoLogicalSize=256T --vdoSlabSize=32G --sparseIndex=enabled --indexMem=2

and xfs Filesystem on top of it. (only) purpose is a backup server for disk images.
(First test with dedup worked fine)

I don't know exactly where to tune the config above to get the most out of the hardware,
(I tried blockMapCacheSize=32G which crashed I couldn't even login and had to reboot.)

So what would be a good configuration for this hardware ?

[bgurney-rh]

Hello,

The VDO Integration Guide (link is to the RHEL 7 documentation, but many of the concepts still apply to VDO in general) has a lot of information on how to set up VDO. There is also a subsection called Tuning VDO, with information on fine-tuning VDO settings.

For the index of this VDO volume, you chose "2 GB memory" and "Sparse mode"; this will configure a deduplication window of 20 TB. How big is your base backup set? If the backup set is much smaller than 20 TB, it may be possible to use a smaller index memory setting.

In terms of memory, a VDO volume requires about 370 MB of memory, plus an additional 268 MB per 1 TB of physical storage. In the case of your VDO volume, if the default 128 MB block map cache size is added, this is about 29.3 GB of memory to start the VDO volume (not including the index memory).

There's a mailing list for VDO development, vdo-devel; please feel free to send an email to the list with questions like these.

[shutdowng0]

Hello,