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5 sata drives, raid recommendations


trumee
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Hi,

I have a N40L with 5 SATA drives. I plan to use ZFS on the drive but wondering whether to go with raidz1 or raidz2. It seems the sweetspot for raidz2 is 6 drives. If I use 5 drives with raidz2 will there be performance problems?

 

Thanks

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Raidz is the equivalent of raid 5 for the Z File System

 

Curious, how big are the drives?

 

Sent from my Nexus 4 using Tapatalk

Edited by dataoscar
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What is "raidz"

 

Raidz is the parity based raid in ZFS. Raidz1 is equivalent to Raid5, where Raidz2 is equivalent to  Raid6.

 

To the OP,  if I remember correctly, the sweet spot in ZFS also depends on whether or not you are using AF drives.

 

I didn't play with it long before I decided to go with a Windows based server.

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From Wikipedia:

 

http://en.wikipedia.org/wiki/Non-standard_RAID_levels#RAID-Z

 

Trumee, I'm afraid most of us don't use the ZFS file system --and RAID-Z really isn't a hardware RAID, so you may not find a lot of answers here.  I'd probably look to a forum that involves the type of OS (Linux, or whatever NAS operating system) you're planning on using.

 

Also, how are you planning on doing this with five drives?  Any method requiring more than four drives  will require a different controller (the N40L onboard supports four drives) or a lash-up of the onboard controller and the separate SATA port, which I wouldn't recommend, due to the different specs involved.  I'd be much more likely to use four drives, or a Smart Array P410 RAID controller to allow five drives in a hardware RAID array.

 

EDIT: Alternately (after reading the ZFS entry on Wikipedia) getting a controller that supports five drives, running them in JBOD, and then running RAID-Z would be a possible option to consider, and probably better if you really need five drives.  Otherwise, I'd run four drives in JBOD on RAID-Z off the internal controller.  Also, I'd ask what your intended purpose is with the N40L, because RAID-Z is going to take some CPU usage right off the top.  Though it's supposed to be a pretty resilient file system, you're relying on the CPU instead of a RAID controller, and the Turion II N40L isn't a super-fast chip.

Edited by LoneWolf
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As you can see, not many on this forum use ZFS; most here chose to use hardware raid setups on Microsoft platforms. I have used hardware raid in the past but have moved to ZFS file systems due to the self-healing properties of ZFS and the inherent silent data corruption issues with hardware raid systems caused by bit rot (been there, done that).

 

There is an abundance of information and opinions out there (many conflicting) about the "best" ZFS pool configurations but the consensus concerning the number of disks in a ZFS storage pool is to use the "power of two plus parity" recommendation. This is for storage space efficiency and hitting the "sweet spot" in performance. So for a raidz1 vdev use three (2+1) or five (4+1) disks. For a raidz2 vdev use four (2+2) or six (4+2) disks. For a raidz3 vdev use five (2+3) or seven (4+3) disks.

 

I would hope you are at max RAM (and it's ECC) on your N40L as ZFS lives on RAM. If not you should consider an OS other than a ZFS-based one.

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Thanks for your answers. The drives will be 3TB WD Reds. I have flashed the unofficial bios so am able to access the 5th SATA using AHCI. The box will also have a 16GB ECC Ram.

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  • 4 weeks later...

Hi,

I have a N40L with 5 SATA drives. I plan to use ZFS on the drive but wondering whether to go with raidz1 or raidz2. It seems the sweetspot for raidz2 is 6 drives. If I use 5 drives with raidz2 will there be performance problems?

 

Based on my research so far, I had planned to go this route using NAS4Free. I setup my N40L for 6 drives and acquired 6x 2TB WD Reds. However, as you've discovered, there is a lack of agreement as to how well such a setup actually works. I was also considering doing this inside a VM on ESXi, but I wondered how resilient the configuration would be in the event of a drive failure. Perhaps the only way to know is to subject it to a torture test and submit the results and benchmarks to the group for discussion. To this end, any advice is appreciated.

Edited by mythic.glyph
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As I previously stated, not many on this forum use ZFS so you'll not get much help here. You'll need to go to other sources (Oracle, NAS4Free, FreeBSD, FreeNAS, etc.) for advice.

 

I think you're expecting a little too much from your N40L to be able to effectively handle a ZFS file system on NAS4Free inside an ESXi VM; if you chose to try it I'd like to know how it performs. And what are you using to connect your 6 HDDs?

 

My N54L is limited by its gigabit NIC, not by its ZFS raidZ2 drive array. But my HDDs are attached to a SATAIII HBA and not the native on-board SATAII ports.

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I think you're expecting a little too much from your N40L to be able to effectively handle a ZFS file system on NAS4Free inside an ESXi VM; if you chose to try it I'd like to know how it performs. And what are you using to connect your 6 HDDs?

 

My N54L is limited by its gigabit NIC, not by its ZFS raidZ2 drive array. But my HDDs are attached to a SATAIII HBA and not the native on-board SATAII ports.

 

I have both an N40L and an N54L, so I can benchmark each. I admit that running ZFS inside ESXi could be asking too much. I might stress test with ESXi on the N54L and install baremetal on the N40L. If this doesn't work out so great, I will get an Intel RAID card like everyone else here.

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