TLER clarification & hardware check

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cjdavies

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Done lots of reading about URE/BER/TLER/etc. & I think I know what I need to do now.

Currently own;
3x 2TB Samsung HD203WI w/ firmware 1AN10003, support SCT control & retain settings through reboot (but not power cycle)

Ordered;
Fractal Array R2 case + power supply

Will order;
3x more 2TB disks that support SCT control & retain settings through reboot - recommendations?
Intel Server Board S1200KP
Xeon E3-1225
8GiB ECC RAM
PCIe controller with at least 2 ports - recommendations?

Intention is to run FreeNAS with the 6x 2TB disks in a ZFS RAID-Z2. Apart from the hardware recommendations (see above) can anybody confirm whether there are any other concerns wrt TLER? Do I simply have to boot linux, use smartctl to set the timeout to 7 seconds, then boot FreeNAS & leave it, or is there anything else I have to do to ensure that in the event of a URE/BER the disk doesn't get dropped?
 

jgreco

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FreeNAS is a software RAID system and is not going to drop the disk. However, you may still want TLER because while the system is busily waiting for the drive to return some status, your clients are screeching to a grinding halt, possibly causing errors and other ugly stuff, so TLER is still a great thing to have. The "needed for hardware RAID controllers" is mainly confusion by people who have some idea of what it does, but not really why hardware RAID controllers might do that - and why software RAID can benefit too.
 

cyberjock

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FreeNAS is a software RAID system and is not going to drop the disk. However, you may still want TLER because while the system is busily waiting for the drive to return some status, your clients are screeching to a grinding halt, possibly causing errors and other ugly stuff, so TLER is still a great thing to have. The "needed for hardware RAID controllers" is mainly confusion by people who have some idea of what it does, but not really why hardware RAID controllers might do that - and why software RAID can benefit too.

+1. Any dropouts will be handled by the SATA/RAID controller. Ideally you aren't using a RAID controller(or flashed it with IT firmware to make it dumb). In the case of SATA or "dumbed" down RAID controllers they don't typically detach under any circumstances unless the hard drive firmware has a lockup. Of course, at that point, the hard drive will have to be power cycled, so it is as good as dead until you reboot anyway.

User "survive" has an amazing list of SATA controllers to choose from somewhere on the forum. He has a link to another webpage that lists a bunch and how good/bad they are. I HIGHLY recommend you find the list and buy from that list. I'd link it but I don't have the link handy and I can't search easily for it at the moment. It's linked in ALOT of places. A lot of people ask the same question you are.
 

survive

Behold the Wumpus
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cjdavies

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Thanks for the clarifications. I'll go with the WD Red disks as they officially have configurable TLER & I'll get the HighPoint Rocket 620 which is based on the Marvell 88SE9128. I've also just found out that the latest i3 processors officially support ECC so I'll go with an i3 3220 to save money/power/heat (the only reason I was going to get the Xeon E3 was because I thought that was the only way to officially get ECC).

The only other question I have is whether there is a sensible way to transition the data from my existing RAID to the new one. I currently have the 3x 2TB Samsungs in a mdadm RAID5 & I want to use them & the 3x WD Red to make a 6x disk RAID-Z2. Can I make somehow set up the 3x WD Red, maybe as some sort of degraded array or as a RAID-Z1, copy the data from the RAID5 onto it & then add the disks from the RAID5 & let it grow into a RAID-Z2? Or am I going to have to look for a temporary 3.6TB of storage? Obviously I want to do this with as little risk as possible - I don't want to risk a URE/BER when growing an array that doesn't have enough parity (yet) to rescue itself!
 
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