SOLVED 9.3 USB vs SSD vs SATA DOM?

[jkh]

The activity profile can be viewed with "zpool iostat freenas-boot". It is not writing much data at all because statistics / logging data go to the system dataset. Of course it should be mirrored. :)

 

[pjc]

Well, if it should be mirrored, why not just use 2 USB sticks? At least they're hot-swappable, unlike SATA DOMs. (I'm only half joking; loss of external access is the big dilemma I see in switching from USB to SATA DOM.)

It's also not immediately clear to me how I'd manage to cram 2 DOMs into the on-board SATA ports, which are quite close together.

 

[cyberjock]

Some DOMs are shaped to fit on boards that have the ports right next to each other. For most home users mirroring isn't exactly a requirement. But in a business environment where downtime=$$$ I'd definitely go the extra mile and spend the extra $20-40 for mirrored DOMs. The first time you go down the DOM would more than pay for itself.

 

[pjc]

Some DOMs are shaped to fit on boards that have the ports right next to each other.

Could you point me to some? I looked at the Innodisk and InnoLite models that @jkh mentioned, but those look too wide. As others have lamented, I don't exactly see a wide variety available.

...in a business environment where downtime=$$$ I'd definitely go the extra mile and spend the extra $20-40 for mirrored DOMs.

I'm definitely pro-mirroring, but now my question is: why not mirrored USB? I can hot-swap those with zero downtime, whereas I'd have to power down the system to replace a failing DOM.

(Alternatively, if there were some way to plug them into eSATA ports, and get power to them, you could presumably hot-swap a DOM.)

 

[cyberjock]

You absolutely can mirror USB drives. The only "push" for SATA DOMs is that they tend to have a MUCH longer lifespan and aren't external. Of course, for some people, being external is a bonus.

I'm not at home so I can't get access to my link for the SATA DOMs. I have seen them though but I couldn't find the darn things with a Google search. :(

 

[jkh]

I'm definitely pro-mirroring, but now my question is: why not mirrored USB?

Because I just don't like USB. :) That said, mirrored USB would certainly be better than a single one. Maybe you could get a USB hub and put, like, 8 cheap USBs sticks in there and mirror all of them! At any given time, there's got to be at least one working, and that's still only like $50 worth of cheap USB drives. ;)

 

[pjc]

:D I hadn't thought about using a USB hub and a boatload of sticks. What could possibly go wrong?...

Seriously, though, I've got 2 USB ports in the front of my chassis and I've got two Cruzer Fit drives that fit nicely under the lockable bezel. Security and hot-swappability both.

They're monstrously slow, of course (21MB/s read, 3.7MB/s write). But that's what ARC is for, right? And the boot drive isn't that busy (right?).

@cyberjock, no rush -- I do look forward to your link.

 

[Norleif]

I'm so confused...
USB thumbdrives only have two major "flaws"... Reliability and speed.
The first "flaw" can be mitigated by mirroring two or more devices.
The second "flaw" is, in my opinion, not relevant. It just means the things you almost never do, like reboot and OS install/upgrade, takes a bit longer.
I have two internal USB ports (not headers) on my new FreeNAS mainboard so the argument for "internal devices" aren't very good either. If your mainboard doesn't have internal USB ports it's still very likely to have headers for standard USB port bracket. In my old NAS, I removed the metal piece from one of those brackets and zip-tied the two loose ports to an internal chassis part. No sticky outy bits on either of my NAS boxes.

Why are people lining up to waste their SATA ports and money on these DOMs, that seems to have a very poor cost-vs-value figure, instead of spending the same resources on more data drives (or ZIL/L2ARC SSDs) ?

 

[solarisguy]

There are USB memory devices that more than OK for a boot/root device.

Try one that is Windows To Go certified: http://en.wikipedia.org/wiki/Windows_To_Go

I do not like their price point, but they surely beat SATADOMs: no need to cannibalize a SATA port or essentially two ports..., they have flexibility of placement (USB ports are everywhere).

 

[diedrichg]

There are USB memory devices that more than OK for a boot/root device.

Try one that is Windows To Go certified: http://en.wikipedia.org/wiki/Windows_To_Go

I do not like their price point, but they surely beat SATADOMs: no need to cannibalize a SATA port or essentially two ports..., they have flexibility of placement (USB ports are everywhere).

I have not read up on the 9.3 notes. Are you saying that USB 3.0 is now supported?

 

[cyberjock]

USB 3.0 has been supported for quite some time. But it's disabled because many USB chipsets do not work with the USB 3 drivers in FreeBSD.

 

[L]

Hey! I just tried zpool split and it works like a charm... Build system with mirrored boot drives, config, run zpool split freenas-boot drive1 drive2. Took the split off drive and was able to easily boot another system.

Gonna try to attach a new drive to system1

 

[L]

Also, you guys finally talked me into usb flash drives. The thing I like about them is in a datacenter, I can easily move a drive to a new server.. I don't have to open a case. Mirrored though..

 

[RobertT]

I'm so confused...
USB thumbdrives only have two major "flaws"... Reliability and speed.
The first "flaw" can be mitigated by mirroring two or more devices.
The second "flaw" is, in my opinion, not relevant. It just means the things you almost never do, like reboot and OS install/upgrade, takes a bit longer.

Regardless you still should backup your config.
Mirroring only gives you uptime if one of your OS devices fail.

Memory based devices are all extremely similar though.
The difference between USB or DOM or Flash drive is the interface used. This could be a speed factor if the interface is the bottleneck.
The reliability is determined by the type of memory chip used in each one (SLC, MLC, eMLC).
Just because it is DOM or Flash doesnt mean that it is really any more reliable than a USB drive.

 

[diedrichg]

My X10SLM-F-O has an on-board USB 3.0 port. How can I find out (shell command) if 9.3 supports the driver for this port?

 

[James Random]

And what about compact flash (via SATA)?

 

[jjstecchino]

I see where this thread is heading.... the route of the windows nonsense! Ohh... my triple striped DOM powered Freenas boots in 9.357 seconds which is a good 0.357 second faster than your SLOOOOOW USB one! Yeah let me squeeze every ounce of performance out of this baby. 70 bucks for a 16 GB DOM and loss of a SATA port vs 10 bucks for a USB stick and one more SATA available does not seem a very reasonable cost/benefit ratio to me. A mirrored USB may make sense, however even in the enterprise setting if you are worried about downtime keep a backup of your config and a replacement USB with a freenas installation and you will be up and running in no time. PS. I like the hello kitty case and matched USB stick! great idea for my next build.

 

[mjws00]

Heh. Amazing mileage out of this thread.

The mirrors are now useful as the zfs boot partition needs a redundant copy to repair instead of puke. USB errors are going to be seen instead of silently ignored. So a poor quality stick might SUCK extra hard. Quality control is not their strong suit. Time will tell how this pans out.

The DOM is just a better chunk of memory with a known good SATA interface. USB (especially USB 3.0) can be flaky under BSD. New chipsets take time to stabilize, but sata is pretty constant. A couple extra bucks to ensure no hassle and extra longevity is a simple decision for a configuration that gets put in production and won't change. Those that need it will have the ports available. Lots and lots of server boards are built with a DOM or two in mind. Of course they often have a usb port mounted as well, which is nice.

CF on SATA is old school cool. Nothing to fear... but we've moved on.

tl;dr Doms all day on a production box you won't touch, mirrored usb on a home rig you'll mess with. SSD if ya got them sitting there and room in the case.

 

[zfrogz]

Is there any drawback to USB other than slow boot times or would it also affect overall performance? Why are writes to the OS drive increasing so drastically over previous versions?

 

[cyberjock]

Is there any drawback to USB other than slow boot times or would it also affect overall performance? Why are writes to the OS drive increasing so drastically over previous versions?

They haven't increased so drastically. The workload has changed slightly because of the switch from UFS to ZFS and the workload type is "random writes" from the appearance of the USB, which is often measured to be 1-3 MB/sec.

Server performance isn't affected because FreeNAS boots up and is loaded into RAM drives, so the performance of the boot device is inconsequential except when actually needing to write or read from the USB stick directly. Off the top of my head that would only be on bootup, boot device scrubbing and OS updates to 9.3.