Convert many ESX VM's from Nexenta/Iscsi to FreeNas/NFS

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jgreco

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For SATA drives, does a single controller with a SAS2 Extender back-plane provide the same performance as a dedicated controller channel for each connection?

No. However, unless you're massively oversubscribed, it isn't usually an issue. For example, the fastest drives these days are a little north of 200MBytes/sec or 1.6Gbits/sec. 12 of those fit fine into a 24Gbps SAS2 4 lane wideport. 24 do not, but even there it is only an issue if you are doing sustained sequential reads on most or all of your disks simultaneously. However if you had 24 SSD's you can easily hit 500MByte/sec per drive, so contention is a serious issue.
 

jgreco

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VMUG membership is free. What's been discussed here is VMUG Advantage for $200/year.

The VMware EVALexperience software gives you access to 9 VMware apps for personal use in a non-production environment.

Think of it as a way to set up a learning lab.


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Wow, that's kinda cool. Maybe a way to discover what some of that extra crap I've never figured out the point of does. I've always wanted to try the virtual desktop stuff but my issue with the 60 day evals of stuff is that by the time I manage to get all the bits in alignment, fires and other stuff have eaten 55 of my days. :smile:
 

jgreco

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I dont have the budget for really "new" SAS disks. So im looking at using used/refurbished SAS disk or new consumer SATA disks.

For used sas disks i found these:
Hitachi Ultrastar HUS723030ALS640 3TB SAS 7.2k 6Gb/s 3.5" Hard Drive for $97


Hitachi HUS723030ALS640 3TB 7.2K 6G SAS HDD
http://www.serverpartdeals.com/hita...jg4Yrb7YVAjXTlk37vWqOz5BgzR-eMvKEIaAoBm8P8HAQ

Which I beleve are not New but Manufacture Refurbished drives.

Any thoughts or recommendations?

Unless you need the extra speed, the headaches of refurbs aren't usually worth it. The WD Red SATA disks are pretty good...
 

jgreco

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A new white label drive usually has a zero year warranty.
 

mbalsam

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On another thread, someone said that if i wanted to run 20+ vm's then i better use 2-way mirros and not RaidZ2.

Thoughts?
 

Mlovelace

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I've always wanted to try the virtual desktop stuff but my issue with the 60 day evals of stuff is that by the time I manage to get all the bits in alignment, fires and other stuff have eaten 55 of my days. :)
You should check out vmware horizon. It's great and very easy to get running.
 

gpsguy

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mbalsam

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Wow. @jgreco great info. These are my take away's

-Must have a large cage since I need 2x the amount of storage as i planned for. Reason: I never want to exceed 50% usage
-Use 2 way mirrors not Raidz2. Go for 3 way if budget can tolerate it.
-I might want to trade off, More Ram for less CPU.
-I only need 2 pci slots - 1 for disk controller - 1 for 10G Ethernet - so i can get a lesser motherboard
-Use Large l2arc SSD's.

Remaining Questions:
- Sounds like more mirrored low cost striped drives are better than fewer but faster SAS drives?
- Why does 3way mirrors have a lot of overhead? Parity Calculations? Is this CPU intensive or Write intensive.

Guys, I really learned a lot today.. FreeNas is the way to go, basically for the community.. With two years of Nexenta with full support I did not received 1/10 the amount of knowledge. Thanks for all the great info!
 

Bidule0hm

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Sounds like more mirrored low cost striped drives are better than fewer but faster SAS drives?

Striped drives doesn't have any redundancy, if you lose a drive you lose the pool.

Why does 3way mirrors have a lot of overhead? Parity Calculations? Is this CPU intensive or Write intensive.

Because you copy the same data 3 times instead of two so you only have 33 % of the total space available for the data.
 

jgreco

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-Must have a large cage since I need 2x the amount of storage as i planned for. Reason: I never want to exceed 50% usage

Correct. But also remember that what really counts is your pool fill percentage, so if you make a typical array, make some LUNs that occupy 50% of them, but have nothing on them, then you've not yet allocated those blocks and you're still very close to 0%. This is why things like TRIM and compression are very useful.

-Use 2 way mirrors not Raidz2. Go for 3 way if budget can tolerate it.
-I might want to trade off, More Ram for less CPU.
-I only need 2 pci slots - 1 for disk controller - 1 for 10G Ethernet - so i can get a lesser motherboard
-Use Large l2arc SSD's.

Yes to all that, but also be sure not to go too small. For a VM system, really, an E3 with 32GB is the smallest you should go, and you're immediately maxxed out on RAM, so that's all a bad choice. A small E5-1620V3 plus 32GB RAM is only a mistake in that it is too small to make good use of L2ARC, but if you buy that RAM in 16 or 32GB sticks, then you're left with a bunch of slots for future expansion.

- Why does 3way mirrors have a lot of overhead? Parity Calculations? Is this CPU intensive or Write intensive.

It has a lot of overhead in terms of disk used. If your design requirement includes something to the effect that a single drive failure should not compromise redundancy, then two-way mirrors is not acceptable. It should be nearly free in every other way, and in fact increases potential read IOPS.

Guys, I really learned a lot today.. FreeNas is the way to go, basically for the community.. With two years of Nexenta with full support I did not received 1/10 the amount of knowledge. Thanks for all the great info!

So, yeah, if you buy a Ford Mustang at the dealership, they'll do a decent job of supporting your car for you, but if you really want to learn about what goes on under the hood, you don't try to engage them, instead you go find the local motorheads where they'll probably be happy to gas on about it (... waits for the boo's ...)
 

mbalsam

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To quote Joe Jackson:

Whats the point of getting sober, if you have to get drunk all over again.

Happy New Year Guys!
 
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