DOM vs cheap SSD vs USB vs PXE

korban

Member
Feb 12, 2013
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Hi everyone,

I recently bought 2 C6100 chassis and I will setup something like Patrick does.

I also have this storage materials:

2 x SATA SSD Plextor M5 Pro 256 Gb
12 x WD20EARX Green 2 Tb

Switching : 2 x Linksys SLM2008 (8 gigabyt ports)

Chassi 1
- node 1 : Pfsense 1 (CARP + PFsync cluster)
- node 2 : ZFS based filer 1
- node 3 : Vhost (ESXi, promox,...)
- node 4 : Vhost (ESXi, promox,...)

Chassi 2
- node 1 : Pfsense 2 (CARP + PFsync cluster)
- node 2 : ZFS based filer 2 (replication of "ZFS based filer 1")
- node 3 : Vhost (ESXi, promox,...)
- node 4 : Vhost (ESXi, promox,...)

For the moment all this stuffs are only theorical, but I ask me how can I manage the filer and nodes boot storages?

1) Generaly do you recommand DOM, cheap SSD or USB to be used as a boot device?
2) For the Pfsense boot device, is it possible to mirror the storage with a software RAID? Unfortunately the C6100 doen't include a RAID controler.
3) The main isue with the filer is: I will use the 6 on board conector because I don't want to buy a HBA to reduce the cost. The 5 port for HDD + 1 for SSD is on only solution. But if usb is not a goor idea for the OS and I can't have a dedicated device for the ZIL, Is it possible and a good idea to "share" the Plextor M5 Pro 256 Gb to work as a Boot OS hdd + L2ARC + ZIL? If yes, is it possible to mirror the ZIL to something else (USB)?
4) To keep my budget as low as possible is it a good idea to use PFsense as a PXE boot server to serv a ISCI initiator ( Sanboot.c32) to boot target stored in the filer?

I hope it will be clear for you because it's a mess in my mind :p

Thanks for your help
 

TheBay

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Feb 25, 2013
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For what it's worth I swear by eUSB/USB SLC SSD's

PXE I wouldn't really bother with personally for this application, great for terminals etc though.

What country are you in as I can get SATA DOM SSD's quite cheap?
 
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Patrick

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Dec 21, 2010
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I've been using older SSDs but I also have stacks of them sitting around so a bit less expensive for me to do so. That said I am thinking PXE is coming soon.
 

MiniKnight

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Mar 30, 2012
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What we really need is a USB type drive that uses SSD grade NAND and controller. Prob now is SAS and SATA spinning drives use too much power so can't use a single cable for data and power on the 7 pins. Getting DOM power in a C6100 would appear to be hard. Didnt see 4 pin connects there
 

TheBay

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Feb 25, 2013
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What we really need is a USB type drive that uses SSD grade NAND and controller. Prob now is SAS and SATA spinning drives use too much power so can't use a single cable for data and power on the 7 pins. Getting DOM power in a C6100 would appear to be hard. Didnt see 4 pin connects there
That's what I use in all my ESXi boxes, eUSB SLC SSD made by ATP
http://www.atpinc.com/p2-4a.php?sn=00000417
&
http://www.atpinc.com/p2-4a.php?sn=00000417



Or in some boxes:

 
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korban

Member
Feb 12, 2013
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www.befr.ebay.be
Mmmm, "eUSB" or "KingSpec 8GB SATA Dom MLC Flash SSD Disk on Module Network PC Solid State Drive" could be a great deal, but I need to check the motherboard of the C6100 because I'm not sure there is a USB connector with pin.

I agree to pay for those quality memory for the pfsense and SAN, but to spare money is it to crazy to play with PXE/ISCI booted Vhost?

Maybe 2 on 4 vhost with eUSB and the 2 other with PXE/ISCI to reduce the possible instability of ISCSI.

I think when the hypervisor is loaded in the server, the main modules are in the ram and the acces to the storage is minimal...

this article make me enthousiast:
How to configure ESXi to boot via Software iSCSI? | VMware vSphere Blog - VMware Blogs

It look to be officialy supported in v4 and 5, then I think they have a good feedback on this method.
VMware vSphere 4 - ESX and vCenter Server
vSphere Documentation Center

Patrick if you try something I'm interested by your experiment.

Thanks for all your help, I will dig deper and share what I will find
 

TheBay

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Feb 25, 2013
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I can get Transcend sata 2gb or 4gb DOM for £14 - £19 but they are MLC, they can use 4 pin motherboard DOM power and they come with cables for standard SATA or Molex power.
 

mrkrad

Well-Known Member
Oct 13, 2012
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the reason for 2gb is direct address mode "SD" likewise in usb. 2GB SD card or usb SLC stick will have massively fast and consistent random and linear i/o patterns. SDHC for >2gb is a sector based system where SD is byte addressed.

If you do a test, you should get something very symmetrical on the read/write speed with a good SLC stick. They look fake as hell and I would only buy them direct ship from the manufacturer. I had to verify with HP that mine was not fake. It looked really fake/ghetto. Benchmarks across the entire 2gb was 100% flat and consistent.

However less than 8gb is not ideal since you can't hold a dump.

So think to yourself:

1. $70 HP usb or sd card that is SLC (probably one chip)
2. cheap SSD SLC (dell 50gb/100gb ) $50-100 new [ebay/amazon] - sata bus.
3. raid ssd dedicated to boot.

Let me tell you the SD and USB rocks. I just did a box with SD, ripped out the P420 and threw in a LSI 9260 - datastore before was 4x2tb 3.5" and now is 4x256gb SAMSUNG SSD.

No issues, booted right up and was ready to go. This is golden. The ability to change both the raid controller and storage subsystem at the same time and the esxi host runs without a hitch. Heck I even redid all of the IRQ's to move the raid card to 5, nic's to 7 , sd to 10,video to 10, rest of usb ports to 11 [ do this in windows 2012 and watch your world fall apart ].

And yeah irq's do matter a ton! the old adage disable everything you don't need floppy,serials,parallel, and run the lowest IRQ to most important still exists, even if its for a short period of time. Having a polling device (Serial/usb) on the same irq as a raid controller or quad nic can cause some serious interrupt storms which can have negative impacts on your overall performance. At least with my older tylersberg 5500/5600 generation - it most certainly matters A TON.
 
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TheBay

New Member
Feb 25, 2013
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I am ok for USB or eUSB with slc.
Good tips with the irq, seriously on modern system I always doesn't care but I will now :)

Do you believe that the eUSB shown by TheBay coul directly plugged in the internal USB port discovered on the c6100 like discuss in this post? http://forums.servethehome.com/processors-motherboards/1638-c6100-extender-board-usb.html
ATP Also sell pendrive USB SLC SSD

If I can get hold of a C6100 to play with I could put any socket you wanted on it :)