The FAQ

[Bidule0hm]

Some sections still need to be filled, it'll take some time so please be patient, and why not help by suggesting questions? thanks ;)

I decided to create a FAQ (as a supplement to the Official FAQ) after reading this thread and this one and also because of the same repetitive questions in 90% of the threads I answer. So, I'll answer them here, once for all :)

Of course this thread will be in perpetual evolution, I'll add some questions and correct some other ones if things changes.

Feel free to suggest me some questions, corrections, ... (by private message to avoid cluttering the thread) ;)

If you want to discuss about this thread, then please use the discussion thread, thanks.

Also I want to say a big thanks to BigDave for the help :)

• Hardware
  • HDD
  • RAM
  • CPU
  • MB
  • HBA
  • NIC
  • PSU
  • Case
  • Fans
  • UPS
  • Misc
• ZFS
  • Pools/Vdevs
  • Datasets
  • Snapshots
  • Replication
  • Misc
• SMART
• System
• Shares and Directory Services
• Network
• Jails
• Plugins
• Misc

 

[Bidule0hm]

Hardware - HDD

Q: Should I use enterprise grade drives?
A: If it's for an home server it's not very necessarily. For a business you might want to use them but it's generally cheaper to use standard grade drives because even if they fail more often they are far cheaper.

Q: Should I use NAS grade drives?
A: Yes, it's recommended because of the TLER support and longer warranty but it's not mandatory. Remember to increase (or disable) the heads parking delay if you use WD green drives, more infos on how to do it here.

Q: What to choose between 5400 and 7200 RPM drives?
A: 7200 RPM drives are noisier, power hungry and run hotter than the 5400 RPM ones so usually it's recommended to choose the 5400 ones over the 7200 ones as the performance difference is pretty small.

Q: Do I need to match the drives sizes?
A: No, you can put a 3 TB drive with a 1 TB one and two 4 TB ones for example. But you'll lose some space on the bigger drives (for example, here it's like if you have four 1 TB drives).

Q: Do I need to match the drives RPM?
A: No, unless you need specific performances (like saturating a 10 Gbe interface for example).

Q: At what temperature should I run my drives?
A: Between 30 and 40 C is the sweet spot. See google's paper for more infos. If you have SSDs setting the temps alerts can be tricky but cyberjock found the solution here.

Q: Can I use SATA drives on a SAS controller?
A: Yes.

Q: Can I use SAS drives on a SATA controller?
A: No.

Q: What is TLER?
A: See jgreco's great thread here.

Q: How do I find the serial numbers of the drives in the GUI?
A: Go to Storage --> Volumes --> View Disks

 

[Bidule0hm]

Hardware - RAM

Q: How many GB of RAM should I use?
A: Minimum 8 GB, NEVER USE LESS than that. Then there is the 1 GB of RAM per 1 TB of drives rule and most of the members start with 16 GB because of the current average pool sizes. This rule is pretty soft, especially for bigger storage sizes, you can have less than 1 GB per TB. If you plan on using deduplication the rule is 5 GB per TB minimum.

Q: Should I use ECC RAM?
A: Short answer: if you care about your data then yes. Long answer: https://forums.freenas.org/index.php?threads/ecc-vs-non-ecc-ram-and-zfs.15449/

 

[Bidule0hm]

Hardware - CPU

Q: Can I use an AMD CPU?
A: Yes but it's not recommended because of the messy ECC RAM support.

Q: Can I use an i3/i5/i7 CPU?
A: Yes but it's not recommended because they don't support ECC RAM. Some i3 should support it but it's currently not 100% sure. Stick with Xeons and Pentium if you want to be 100% sure.

 

[Bidule0hm]

Hardware - MB

Q: What MB should I use?
A: Server grade MBs is the way to go. SuperMicro makes really good hardware and is well known in the FreeNAS community. ASRock Rack is also a good choice.

Q: I have a desktop motherboard, can I use it?
A: If you care about your data then no. It's recommended to use ECC RAM and only server grade hardware support it.

Q: Is there a performance difference between SATA II and SATA III ports?
A: For regular HDDs, no. For SSDs it might be.

Q: Is there a performance difference between SATA ports vs. SAS ports?
A: No. SATA II and SAS are both 3 Gb/s, and SATA III and SAS 2.0 are both 6 Gb/s.

Q: How the SuperMicro MB model numbers works?
A: Look at this thread.

Q: I have a problem with my X10 SuperMicro MB, what should I read first?
A: Look at this thread before doing anything else.

 

[Bidule0hm]

Hardware - HBA

Q: What HBA should I use?
A: The venerable IBM M1015 card is well known to work very well with FreeNAS (be sure to flash the firmware to the IT P16 version for FreeNAS 9.3 or IT P20 version for FreeNAS 9.3.1 before using it). The second choice would be a HighPoint card but be very careful because some models work, some don't, read this thread first.

Q. I have an LSI/Avago 2008/2308 HBA. What firmware should I run on it?
A. Avago tests their hardware with specific firmware/driver combinations. At the time of this writing, FreeNAS uses driver version 21, which should use phase 20 firmware.

Q. Should I use IT or IR firmware on my LSI/Avago HBA?
A. The reality is either can be used. FreeNAS doesn't include the software to use the IR features of cards flashed with IR firmware. However, in the interest of KISS we always recommend IT firmware.

Q. I have an LSI/Avago 3008 HBA. What firmware should I run on it?
A. For reasons known only to Avago, these controller use a firmware version one less than the driver version. At the time of this writing v13 is the current driver, which requires phase 12 firmware.

Q. I have an LSI/Avago MegaRAID or other RAID controller. Can I use this with FreeNAS?
A. ZFS works best when it has direct access to your disks. It can be successfully used with a RAID controller but it's important to disable consistency checks on the RAID controller as well as write caching. In some cases the RAID controller support disk passthrough, which is preferred to single disk RAID 0 or creating a RAID volume.

Q. What are the best SATA controllers for SSDs?
A. For most spinning disks controllers don't matter. Almost any controller will be faster than the disks. For SSDs the preferred controller is onboard intel SATA ports.

Q. What is the best FC hardware for FreeNAS?
A. Qlogic.

 

[Bidule0hm]

Hardware - NIC

Q: What NIC should I use?
A: Intel. Never use Realtek or other crappy NICs. For 10 Gb network Chelsio is also a good brand.

 

[Bidule0hm]

Hardware - PSU

Q: What PSU should I use?
A: You should use a PSU that is at least 80 Plus Gold certified and that is from a good brand (SeaSonic, Antec, Corsair AX-xxx or HX-xxx, ...). Never use a crappy PSU to save $30 because bad quality power can eat other components slowly (especially the drives) and/or generate errors (especially SATA CRC errors). Also if it fails it can kill other components of your system too, let alone the fire hazard with really crappy PSUs.

Q: What power do I need?
A: A quick rule is to count 2 A per drive and from 10 to 15 A for the rest of the system on the +12 V rail. It's not a precise rule so you should look more precisely at the power consumption of each component but it'll give you a rough idea of your needs. Look at this thread for more infos.

 

[Bidule0hm]

Hardware - Case

 

[Bidule0hm]

Hardware - Fans

Q: Can I replace my 80 mm fans by 120 mm ones to lower the noise?
A: In general yes, but if you use some bay with trays for the HDDs then no. The problem is due to the pressure needed to force the air between the HDDs and the trays. For more info look at this thread.

 

[Bidule0hm]

Hardware - UPS

Q: What is the difference between Offline/Standby, Line-interactive and Online/Double-conversion UPSs?
A: An offline UPS is the most basic one and just switch the load between the grid and the battery powered internal inverter when the grid fails. A line-interactive UPS is the same but adds a multi-taps autotransformer so it can accommodate small under and over-voltages without using the batteries power. In an online UPS the load is always run from the internal inverter so there's no switch time.

Q. Which UPS is recommended?
A. For the latest UPS recommendations from other FreeNAS users, click here.

 

[Bidule0hm]

Hardware - Misc

Q: What hardware is recommended?
A: Look at the Guide to FreeNAS Hardware Design and the Hardware Recommendations thread.

Q: Can I use a hardware RAID controller?
A: No. NEVER ever use hardware RAID with ZFS, ZFS *is* your RAID controller.

Q: Can I change/upgrade my MB/CPU/RAM/HBA without destroying the data?
A: Yes. The data is very well separated from the rest of the system, you can also change the connection order of the drives without any problem if you want.

Q: Why IPMI is so useful and wonderful?
A: You don't need to connect a keyboard, mouse and monitor to the server (even to access the BIOS for example) and you can remotely mount ISO images so you don't need to use a USB stick for that.

 

[Bidule0hm]

Hardware - Reserved

 

[Bidule0hm]

ZFS - Pools/Vdevs

Q: Can I add a drive to expand a pool that becomes too small?
A: No if you want to keep the redundancy (and it's likely the case) because the only way to add a drive is to stripe it to the pool. However you can add a new vdev to an existing pool (for example adding a RAID-Z2 vdev of 6 drives to an existing pool comprised of a 6 drives RAID-Z2 vdev) or replace the existing drives one by one using the replace procedure of the manual (and let the resilver process finishes each time) by bigger drives, when the last one will be replaced the pool will grow automagically.

Q: How many drives can I put in one vdev?
A: The recommended maximum number is 12. If you have more drives than that then just do 2 or more vdevs.

Q: How many vdevs can I have in a pool?
A: There's virtually no limit.

Q: If a vdev fails, will I lose my entire pool?
A: Yes, vdevs are striped to form a pool, that's why you don't want to use single drive vdevs.

Q: Is a scrub required/recommended after replacing a failed drive?
A: No because after replacing a drive the resilver process takes place and a resilver is similar to a scrub. But if you're a bit paranoid you can always do a scrub, no problem.

Q: How often should I setup the scrubs?
A: I recommend at least one scrub per 2 weeks. You can see Cyberjock's schedule here and mine here (in the Misc section) for example.

Q: How do I view the results of the last scrub of my pool in the GUI?
A: Go to Storage --> Volumes, click on the pool name at the top to highlight it and then click on the Volume Status icon at the bottom.

 

[Bidule0hm]

ZFS - Datasets

Q: Why there's two nested main datasets in the Volumes tab?
A: It's normal. The first one is in fact the pool and the second one is an implicit dataset often called root dataset on the forum.

Q: Why the used/available spaces of the two nested main datasets are different?
A: The first one (pool) includes the parity space but the second one (root dataset) only refers to the data space.

 

[Bidule0hm]

ZFS - Snapshots

 

[Bidule0hm]

ZFS - Replication

 

[Bidule0hm]

ZFS - Misc

Q: Do I need to format the drives before using them?
A: No, they will be automatically formatted at the pool creation.

 

[Bidule0hm]

ZFS - Reserved

 

[Bidule0hm]

SMART

Q: How often should I setup the SMART tests?
A: I recommend at least one short test per week and one extended test per month. You can see Cyberjock's schedule here and mine here (in the Misc section) for example.