[kwlug-disc] Docker Host Appliance

[Mark Steffen]

A little late to the discussion but I’ll add my 2 cents..

I’m using ZFS for VM storage.  I’m not using a SLOG or L2ARC since all drives are SSDs.  Works well and seems to wear the drives less than hardware RAID.  Favourite feature is ZFS send/replication, great for backups/DR even over the Internet since it only sends the diffs each time.

I believe you can have a pool made of different vdevs of different drive sizes, where I think you want to be more careful is that the vdevs are made of similar performing drives or the pool may be only as fast as the slowest vdev since ZFS will spread data across all vdevs in the pool (it doesn’t rebalance when you add a new vdev however IIRC).  Vdevs can be made of differing drive sizes but the Vdev’s size will only be the smallest drive in the vdev x number of drives (and type; mirror/z1/z2/etc).  While a mishmash will still technically work, I still think it makes sense to have a pool made all from the same size/speed drives and identically configured vdevs (since, for example, a mirrored vdev is going to have different performance characteristics than a RAIDZ2 vdev, etc.)

Mark

> On Jan 18, 2023, at 9:26 AM, Hubert Chathi <hubert at uhoreg.ca> wrote:
> 
> On Tue, 17 Jan 2023 12:33:51 -0500, Chris Irwin via kwlug-disc <kwlug-disc at kwlug.org> said:
> 
>> On Tue, Jan 17, 2023, at 11:40, Hubert Chathi wrote:
>> 
>>> FWIW, you can disable COW on btrfs for certain files, if you want better
>>> performance for databases/VM images by using the +C file attribute .
> 
>> True, but if you're disabling COW, you're probably using the wrong
>> filesystem.
> 
> The ideas is that you may not need COW for those files (since some
> databases have their own integrity checking mechanisms), but want it for
> your other files.  And you don't want to use a whole separate filesystem
> for your DB files.
> 
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