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If the option for multiple RAID groups in the same volume was there when I was running some experiments with the new FlexRAID options before comitting my new NAS to production, it was not obvious how to do so. An article on how to use these new functions is clearly called for.
The 6.7 documentation does describe it.
In ReadyNAS OS, a large RAID volume can be organized into RAID groups. RAID groups can improve performance by distributing I/O across more of the disks. During the process of creating a volume large enough to support RAID groups, ReadyNAS OS selects an appropriate RAID group structure for you.You can override this automatic structure before the volume is actually created.
and
If more drives than the minimum necessary for the selected RAID level are available, the Number of RAID Groups, Number of drives for RAID Group, and Remaining drives allocated to Global Spare fields are active.You can chose to organize the volume with RAID groups, or assign disks to the global spares pool, or a combination of the two.
I agree it isn't enough - it sketches out what you can do, but doesn't say how.
I've passed on the suggestion for a kb article. Some examples with screenshots would be very helpful.
[edit] I know this was already posted by @Skywalker but just regurgitating it. [/edit]
X-RAID will only factory default to XRAID RAID 6 if you are using 6 disks in a chassis that has more than 6 bays. Bay count 6 and below will factory default RAID 5 but 8, 12 bay units will factory with RAID 6 XRAID.
[edit] I know this was already posted by @Skywalker but just regurgitating it. [/edit]
X-RAID will only factory default to XRAID RAID 6 if you are using 6 disks in a chassis that has more than 6 bays. Bay count 6 and below will factory default RAID 5 but 8, 12 bay units will factory with RAID 6 XRAID.
*X-RAID will only factory default to XRAID RAID 6 if you are using 6 disks or more in a chassis that has more than 6 bays.
I took a 6-drive array from a 6-bay unit and put it in a 12-bay unit. So, it started as RAID5 and the addition of the 7th drive caused it to change to RAID6. If I had started with 5 and added a 6th in a 6+ chassis, would it have converted then, or still on the 7th? The RAID calculator shows it happening on the 7th.
The exact situation you describe was tested and is included in my report. The reshape to RAID6 occurs at the 7th drive (unless you add 5 drives or more at once to a RAID1).
Even though there is more bays displayed than that, the RAID calculator is based on volume creation rules for "6 bays or less". It doesn't support expansion, which sometimes needs to know the history of the volume.
If the option for multiple RAID groups in the same volume was there when I was running some experiments with the new FlexRAID options before comitting my new NAS to production, it was not obvious how to do so. An article on how to use these new functions is clearly called for.
The new features of Flex-RAID came in 6.7.0 iirc.
For the doc, I don't see that coming anytime soon, if ever. The old features aren't even documented.
FWIW, the new features are pretty well explained in this white paper:
I'm impressed by this document and was clearly wrong.
It's a shame there isn't something like that for X-RAID though.
The first page should say "since F/W 6.7.0" to make it clear, from the beginning.
I'm pretty sure "expanding" a JBOD (while remaining a JBOD) used to be possible, though I think it would be described here as adding a group. Was that changed, is the doc wrong or am I wrong?
It seems weird to allow concatenation of multiple RAID0 groups. It's against the purpose of using RAID0.
What is meant by expanding a RAID1? Does it mean having multiple mirrors? Isn't that adding a parity?
Why not allow to convert a RAID1 to RAID10 by adding a RAID1 group as striped? (Being crazy, allowing to stripe multiple RAID1 groups with multiple mirrors.)
It seems weird to allow concatenation of multiple RAID10 groups. Shouldn't only striped be allowed? Same as RAID50 and RAID60.
There is no explanation whatsoever about vertical expansion in that document though. If this remains unchanged, Flex-RAID doesn't create secondary RAID arrays, it only extend the existing one(s) in place once all the HDDs are upgraded.
I don't want to be annoying with spelling - I understand if I am, but this document mixes Flex-RAID and FlexRAID. It would be nice if that was consistent. Same for X-RAID being called XRAID.
