amuck-landowner

BBU vs ZMCP?

Geek

Geek

Technolojesus
Verified Provider
I've recently introduced another machine into the production environment.  My preferred HDD configuration for OpenVZ has always been either 4x4TB or 4x2TB REs, with BBU.  This newest machine is for :gasp: KVM, and was provisioned with ZMM cache protection rather than BBU.

TBH this is the first time I've worked with this type of controller. I understand ZMM uses capacitor+flash, but is this going to be an ideal configuration down the line?  I'm just beginning to get some research on this.  Would someone mind having a peak at what I've set in arcconf so far?

http://x3.jetfi.re/dev/arcconf.txt

I've included a quick dd and hdparm output, as well as an example of how each of the four drives are configured.  I've read that the background consistancy check can be heavy on the I/O at times, but if it's safer to run it that way, I'll turn it on.

Thanks so much in advance guys!

John
 
N

Nett

Article Submitter
Verified Provider
Is ZMM something like LSI's CacheVault?

CacheVault is basically a better BBU (with a different technology) that holds power longer, 3+ years vs 3 days on a typical BBU.
 
Geek

Geek

Technolojesus
Verified Provider
%s/peak/peek :)

Yeah, that's the impression I got after reading through this - http://www.adaptec.com/nr/rdonlyres/e2c8f4f4-921e-4e7d-90be-0ef41aa6557c/0/intro_zmcp.pdf

I see these caps charge instantly at boot time.  That's much nicer than having to disable write-back for a couple days to run a cap test on the BBU.

I'm also reading that ZMM seems to have been around a while now -- most of the articles I've read were authored back in 2013. Dunno if that's a good thing or not. If it pre-dates BBU, or is generally dated, is it worth it/safe?

I believe I would only need to turn on Copyback if I had a hot spare.  Still not certain about the background consistency checks. It seems like it would be smart to enable. I imagine disabling it would prevent me from receiving real-time alerts if I lost a drive.  I can't find the damn URL where I read that it may put a slight strain on the disks.  Right now I've got ~25 guests from here in Portland that I migrated over, and the benches I've run over in your 'hood averaged between 340 MB/s and 375 MB/s (from about 230 MB/s prior to tuning the controller and some streamlining on the host, see https://www.petabyet.com/result/2015-05-21-c679f4d385ae1d68bff53c878bcadcd1/)

If anyone has any recent articles I could read up on, I'd be much obliged if you'd share them with me.  :)

John
 
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Geek

Geek

Technolojesus
Verified Provider
Also, the fact that the controller supports hybrid configurations is a plus as I've been tossing around the idea of deploying a hybrid the last couple of months. 
 
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