Old time fella looking for a refresher

[opentoe]

Hi. I believe this is the first time posting here. I'm 51 years old, been running several NASssss over the years and ended up with a 160TB unraid system. Been using unraid since V3 was out, so that's a very long time and many years. My only gripe is the slow write speeds. To speed up write times unraid uses a weird write method. You basically have a spot to write your data. Fast as the destination drive will go. Awesome. But that data does not really end up in the array until a special mover program which kicks in at night really physically moves the data, which is NOT the speed of a destination drive, but the speed of entire array itself, which usually is 80-100 MB/sec. I have been really impatient these days when copying files. My home network is now fully 10GBE, so that copying messness to unraid is slowly irritating me. I do love the community and that platform but I think it may be time to switch up to something more advanced and faster. For those Trunas guys out there, what is the type of write method Trunas uses? I have been reading the forums a lot here and how Trunas works, but would like to hear from users that use it everyday and maybe some users that came from unraid. I'm actually building my final server. Going from a 24 server case to a 20 server case. Already have the mainbord, memory, PSU. The migration from unraid (if that even happens) will be a challange. I can't afford to buy all new 20TB drives, so I will need to have unraid up and trunas up at the same time. Have to see how Trunas lets the user add/remove drives. Same size drives? Different size? All that jazz. Well, thanks for reading and it hope to hear from you soon!

 

[Arwen]

Welcome to the forums!
And welcome to the world of ZFS!

You appear to need lots of reading. Some answers:

• ZFS does not have a write cache
• ZFS does copy on write, which can fragment constantly changing files
• ZFS normally uses async writing, so the writes end up in RAM, and after a bundle is collected, burst written to the disks
• You can not add or remove disks willy nilly on ZFS. Their are some cases like Mirrors in which you can add Mirror vDevs or remove them. But, RAID-Zx vDevs are immutable at present.
• Different sized drives are possible, but their are limitations. One is that a vDev made of mixed sizes will use the smallest drive as the base size.
• It is possible to grow a ZFS vDev, (or pool if you only have 1 vDev), by replacing all the disks with larger ones. But, it won't grow until all the disks are replaced and re-synced.
• TrueNAS is also a commercial product, so their are some trade offs. Like requiring dedicated boot drive(s).

Here are some suggested readings:

Introduction to ZFS

This is a short introduction to ZFS. It is really only intended to convey the bare minimum knowledge needed to start diving into ZFS and is in no way meant to cut Michael W. Lucas' and Allan Jude's book income. It is a bit of a spiritual...

www.truenas.com

Terminology and Abbreviations Primer

We realize that new users have a lot to learn when they come to FreeNAS. There's a certain amount of confusion added to discussions when users pick random/approximate terms to describe things. I've spent a lot of time quietly trying to...

www.truenas.com

ZFS Storage Pool Layout

This amazing document, created by iXsystems in February 2022 as a "White Paper", cleanly explains how to qualify pool performance touching briefly on how ZFS stores data and presents the advantages, performance and disadvantages of each pool...

www.truenas.com

 

[opentoe]

Thank you! I will do some reading!