Zfs nexenta: howto create log/cache

janhoedt
janhoedt used Ask the Experts™
on
Please advise howto create cache/logdeive. When I try to create a mirrored volume for log, it says that I have to create a volume first ...?

The error exactly:

Cannot create volume only with log or spare disks: Please add disks to pool This configuration will be used to create volume.

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Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Commented:
did you install Napp-it?

do you have spare disks, to add as log (ZIL) or cache (ARC) ?

to add cache (arc)

zpool add tank cache c4t2d0
zpool add tank cache c4t3d0

where tank is the pool name, and c4t2d0 and c4t3d0 are disks, cache cannot be mirrored.

to add log (zil)

zpool add newpool log mirror c0t6d0 c0t7d0

where newpool is the pool, and c0t6d0 c0t7d0 are disks

Author

Commented:
Thanks, but I really like the gui to configure, helps me to understand zfs concepts. Does screenshot above help to clarify my problem?
It says to add disks to pool, but when I add disks to pool, I don t see option to make log or cache disks.
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Commented:
you have to add logs and cache to a pool.
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Author

Commented:
Both to same pool?
VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
Commented:
yes, both ZIL (log) and ARC (cache) are allocated to a pool.

if you open a console, using Nexenta GUI and type zpool status, you will see the status and disks added to your pool.

did you not add log and cache disks at creation?

Author

Commented:
Ok, found it: you need to "grow" the existing volume (for me the zraid on SATA disks), then you can choose disks for log and cache.

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