IX Hardware - Read & Write Cache - Is this misleading?

General Discussion
1

[Note that I am not saying that IX are doing anything illegal / immoral / deliberately misleading here.]

I was poking around the TN website looking at the H-Series. Not because I wanted one, but I was just curious.

I came across this.

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Now one of the frequent issues we have on this forum (and on reddit) is that:

  1. L2ARC is not really a read cache - not as most think of it
  2. SLOG is definately not a write cache

Yet new users often think that an L2ARC and a SLOG are part and parcel of a new build - which they aren’t.

Now I acknowledge that a business use case may require L2ARC and or a SLOG but to call them read and write cache… seems misleading and confusing to me.

3 Likes
2

If it isn’t deliberate, their marketing team are irresponsible to the point of recklessness. I’m not sure which is worse.

3

I don’t know if it is ZFS itself or iX Systems TrueNAS. Run ‘zpool status -v’ and what do those two devices show as? Log for SLOG and Cache for L2ARC. The GUI in Fangtooth just matches the CLI. What does the ZFS documentation say?

4

There’s the terminology used and there’s also the sizing of that read cache maxing out at 6.4 TB. I would describe that as well within the specialist configuration territory. An odd flex.

Another alternative is that they actually mean a Special VDEV, but that seems less likely due to the low redundancy a two device mirror would provide.

5

:point_up:
This is the key for us providing help here on the forum.

For the commercial side, selling harware for money, the terminology is inaccurate, but I may understand that the sales team wants to reach buyers who are NOT ZFS admins (including the N+1 of the sysadmin and the beans counters).

6

I knew it! They said I was crazy! I was right all along!