Boot device Supermicro SATADOM or SATA SSD 2.5

[dror]

Hey friends,
Now my system is running on 2 usb stick that always fails.
I have this system - Supermicro SYS-1028U-E1CR4+
I am debating whether to purchase 2 SATADOM and make a mirror between them or purchase 2 2.5 inch SSD and make a mirror between them.
what do you think ? What is better and safer? The consideration here is to lose 2 2.5 inches of free space for the boot than for the pool.
Is SATADOM reliable? Should mirror be made?
I should mirror boot device at all ? Does it give an advantage in such a case?
It's an enterprise environment.

Thank you!

 

[Patrick M. Hausen]

The Supermicro brand SATA DOMs have proven very reliable for us, no failure after more than two years of constant use. If you plug them into one of the orange coloured connectors you do not even need the tiny power cable on Supermicro boards.

They are a bit expensive, though. Depends how "neat" you prefer things inside your system. ;)

HTH,
Patrick

 

[dror]

The Supermicro brand SATA DOMs have proven very reliable for us, no failure after more than two years of constant use. If you plug them into one of the orange coloured connectors you do not even need the tiny power cable on Supermicro boards.

They are a bit expensive, though. Depends how "neat" you prefer things inside your system. ;)

HTH,
Patrick

Thanks for your response.
I have 2 orange ports for superdom, I should mirror them? If I understand right, satadom is very low at writes OP, You mirror them?
This is very important to me becuse this enterprise environment.

 

[Bozon]

You mirror the FreeNas boot drives for redundancy, not speed. Very little information is written to the boot device, and most of the operating system ends up in memory cache, while the system is up, so the speed of the device only impacts booting. SATA Dom's are expensive, but they do keep drive bays empty, and SAS and SATA ports empty. They are also designed specifically to do the job that you want done, which is to hold the operating system, for booting, and execution.

 

[Patrick M. Hausen]

I have 2 orange ports for superdom, I should mirror them? If I understand right, satadom is very low at writes OP, You mirror them?

We do and you should, too.

Patrick

 

[Johnny Fartpants]

I choose to use 2.5inch SSD's (attached to 3.5inch caddies) as they are easier to get out if/when then need to be replaced. SATADOM's are a bit trickier. That being said I guess it depends on the hardware you are using. I use 2U rackmount servers attached to JBODs so the drives are hot-swappable. The idea of having to de-rack/pull-out a server just to replace a failed SATADOM doesn't make sense for us.

Regarding mirror then I would say yes mirror your boot devices.

 

[dror]

I choose to use 2.5inch SSD's (attached to 3.5inch caddies) as they are easier to get out if/when then need to be replaced. SATADOM's are a bit trickier. That being said I guess it depends on the hardware you are using. I use 2U rackmount servers attached to JBODs so the drives are hot-swappable. The idea of having to de-rack/pull-out a server just to replace a failed SATADOM doesn't make sense for us.

Regarding mirror then I would say yes mirror your boot devices.

You're right, to replace satadom needs to shut down the server and that's a disadvantage.
But the consideration here is to keep as many SAS / SATA ports free as possible for the zfs pool.
I know you need to do mirror to boot but since it is a satadom whose performance is weak I realized it is dangerous and can cause satadom to fail quite quickly, Is it true or I have nothing to worry about ?

 

[Patrick M. Hausen]

The mirroring itself does not put any additional write load on the DOM. Blocks that are written simply go to both disks instead of one. There is no repeated copying of data or what you might be implying ;)
And as I wrote the Supermicro ones are made specifically for OS installation. So they are robust for writes. We run a stock FreeBSD on a pair of them, logging, updates and all. No problems so far.

HTH,
Patrick

 

[dror]

The mirroring itself does not put any additional write load on the DOM. Blocks that are written simply go to both disks instead of one. There is no repeated copying of data or what you might be implying ;)
And as I wrote the Supermicro ones are made specifically for OS installation. So they are robust for writes. We run a stock FreeBSD on a pair of them, logging, updates and all. No problems so far.

HTH,
Patrick

Thank you very much it helps!
What do you think ? Use the 32 GB or 64 GB version?

 

[Patrick M. Hausen]

32 is more than enough.

 

[Bozon]

The mirroring itself does not put any additional write load on the DOM. Blocks that are written simply go to both disks instead of one. There is no repeated copying of data or what you might be implying ;)
And as I wrote the Supermicro ones are made specifically for OS installation. So they are robust for writes. We run a stock FreeBSD on a pair of them, logging, updates and all. No problems so far.

HTH,
Patrick

Here is a question on a FreeNAS server, how much writing is done to the boot disk anyway? I would think almost none, comparatively.

Mirroring doesn't put extra load on a drive, as each drive only gets as much information as it would have gotten if it wasn't mirrored. Having the extra device increases your reliability greatly.

For example, if one drive is 99.999 % reliable, 2 drives mirrored is ( 1 - (.00001*.00001) ) 99.99999999 % reliable. Because both drives would have to fail. (Edited because formula was off.)