zpool with multiple types of RAIDZ?

[Lastb0isct]

Hi All,

I am curious if this is a big no-no or if it is okay? I am just introducing 10 new discs into my machine and they have been used in the past. They have a lot of hours on them and i want to make sure that if one dies i will have enough time to replace it before another dies. To get around this i want to do a RAIDZ2 for these new zpools.

This is the current setup i have for the zpool i want to extend:

RAIDZ1 - 5x4tb HGST - BRAND NEW

I am not worried about the new ones dying which is why they are setup in a RAIDZ1. The 10 new discs that i have are each 1TB and i wanted to throw in two more vdevs as RAIDZ2.

I am messing around with it and was able to get it to work as such with the manual setup.

Is this a big no-no?!

 

[Scharbag]

RAIDZ1 - 5x4tb HGST - BRAND NEW

I am not worried about the new ones dying which is why they are setup in a RAIDZ1.

:D:D:D

Do you have a properly provisioned and tested backup of all of you data that will be on this pool? If not, you are playing with fire (unless the pool is used to store temporary data only). RaidZ1 with large drives is just not a good idea.

You "can" do just about anything with ZFS. Does not mean you should.

Here is an older blog that seems to have a few solid recommendations.

Cheers,

 

[Lastb0isct]

If you read my question, that was not what i was asking at all. I am fine with RAIDZ1 on those drives. This pool is comprised of data that can be replicated and is backed up. Please, don't roll your eyes at me, lol.

My question is, does mixing RAIDZ types within a zpool cause issues.

Edit: also, i don't think your information is quite current. RAIDZ1 is allowable for your fault tolerance. I don't believe that its "not recommended", as it depends on your use case.

 

[Scharbag]

Of course the Raid level is dependant on your use case. Z1 on large drives poses increased risk of system downtime while waiting to restore from a backup. You need to understand your requirements and choose accordingly.

Just because your drives are new does not guarantee that they will not fail. The HGST drives are great but they still have a failure rate. And if the drives contain data that is not overly important or is properly backed up, I would suggest you use the 10 drives in a single RaidZ2 vDev. That way, you pick up 2 more TB of space.

From what I have read, mixing Raid levels in a pool is not recommended. Will it work, likely. ZFS would also allow you to build a 60 drive RaidZ1 vDev, but that is also not recommended.

Cheers,

 

[pirateghost]

Edit: also, i don't think your information is quite current. RAIDZ1 is allowable for your fault tolerance. I don't believe that its "not recommended", as it depends on your use case.

http://www.zdnet.com/article/why-raid-5-stops-working-in-2009/

https://www.reddit.com/r/freenas/comments/1ubebu/stop_using_raidz_seriously_just_stop_it/

and yes, it is HIGH on the 'Not Recommended' list....

 

[Lastb0isct]

http://www.zdnet.com/article/why-raid-5-stops-working-in-2009/

https://www.reddit.com/r/freenas/comments/1ubebu/stop_using_raidz_seriously_just_stop_it/

and yes, it is HIGH on the 'Not Recommended' list....

You link an article from 2007 and a reddit post with 1 upvote...lol. Guess my question is not going to be answered here. Thanks for the help.

BTW, from that reddit post, the top most comment:

"This is highly paranoid. The beauty of ZFS is that a single error during resilvering does not corrupt the entire raid as it would in traditional raid5. It's not a binary, rebuild succeeded or rebuild failed scenario. If this happens, you will experience unrecoverable errors on select files contained in the corrupted blocks and zpool status will tell you what those files are.

Obviously that isn't great, but it's not nearly as dangerous as this post makes it out to be. And of course you have backups, so you can restore those couple of corrupted files if they should happen to appear."

 

[pirateghost]

Guess my question is not going to be answered here.

https://forums.freenas.org/index.ph...ng-during-rebuild-and-more.43395/#post-285845

https://news.ycombinator.com/item?id=8306499

http://www.standalone-sysadmin.com/blog/2014/11/recalculating-odds-of-raid5-ure-failure/

http://www.raidtips.com/raid5-ure.aspx

If you actually do some research, you will see it plastered all over these forums when people are discussing new builds or potential layouts of their disks.

With the stress level put on the remaining disks in the array during a resilver, it is stupid to think that RAIDZ(1) is infallible. With a RAIDZ1/RAID5 if you lose a second disk while the resilver/rebuild is taking place (which given the size of the disks/pools we create holds a higher probability than you think), YOU LOSE EVERYTHING, not just a few unrecoverable sectors or corrupted blocks. You will be restoring ALL data from your backups.

If you are cool with recovering all your data at some point, more power to you, but don't sit there and say that it isn't a 'Not Recommended' setup.

 

[Lastb0isct]

I am saying it is determined by your fault tolerance. How do you not get that? You guys are FAR BEYOND the point of this post. So please, stop posting shit off-topic!

Edit: I also never said that its infallible. My HGSTs barely have any hours on them. These new 1TB disks have over 20k hours each. So, i am interested in the mix of RAIDZ1 & RAIDZ2.

 

[pirateghost]

I am saying it is determined by your fault tolerance. How do you not get that? You guys are FAR BEYOND the point of this post. So please, stop posting shit off-topic!

The topic of these forums is keeping your data safe. If you think that we don't care about people keeping their data safe, we wouldn't say anything to you about it.

When you post something that we obviously disagree with, especially considering you admitted you have never seen us NOT RECOMMENDING such a setup, should we just not mention the dangers that you are adding to your system? Did you not choose FreeNAS because it protects your data? You expect everyone to sit here and watch you destroy your data?

Your attitude is most unwelcome. You can take it somewhere else if this is how you are going to treat those that are trying to point out the errors that we see with this setup.

You were warned, you obviously don't want to listen.

 

[Lastb0isct]

I have determined that RAIDZ1 is okay for my needs on these drives. I have seen it posted all over the place that people don't trust a RAIDZ1 with data that matters. This data doesn't "matter" in that way. This is why i set it up as a RAIDZ1.

I know that these new drives have a lot of hours on them and i want to have a little more fault tolerance for them since they are 5+ years old and have 20k+ hours on them.

I am not very active on these forums, but i have been running freenas for 5+ years as well. I know my way around a system. It is not an error in my setup it is TOLERATED RISK.

I asked a question and it still has not been answered. You are just hounding me on a portion of my system that has been up and running that way for 3+ years. I have my setup the way I want it. The data on this zpool is replaceable. Please, let that sink in. People have different tolerances for data protection. My RAIDZ1 is operating just fine for my needs.

 

[pirateghost]

actually it was answered in post number 2, but I suppose you were too busy focusing on telling everyone to shut up to read it

https://forums.freenas.org/index.php?threads/zpool-with-multiple-types-of-raidz.43545/#post-287242

 

[pirateghost]

http://doc.freenas.org/9.10/freenas_intro.html#zfs-primer

 

[Lastb0isct]

I read that post and it just said "you can do anything with ZFS". Doesn't really answer my question about difference types of vdev's in the same zpool. I have not found any information on that and I do not need a primer on ZFS. I'm quite versed.

You remind me why i avoid this forum so often...

 

[pirateghost]

http://constantin.glez.de/blog/2010/06/closer-look-zfs-vdevs-and-performance

 

[pirateghost]

I read that post and it just said "you can do anything with ZFS". Doesn't really answer my question about difference types of vdev's in the same zpool. I have not found any information on that and I do not need a primer on ZFS. I'm quite versed.

You remind me why i avoid this forum so often...

Did you bother to click his link, oh wise one?

 

[Lastb0isct]

Yes, i did and it seems outdated. Even says not to use different disk sizes in the same zpool...yet we have ZFS Pool Expansion now.

I was looking for more current answers, but i guess it will suffice.

 

[Scharbag]

I read that post and it just said "you can do anything with ZFS". Doesn't really answer my question about difference types of vdev's in the same zpool. I have not found any information on that and I do not need a primer on ZFS. I'm quite versed.

Then why did you ask?

Simple Google search found this:

• Other than a spare, SLOG and L2ARC in your hybrid pool, do not mix VDEVs in a single pool. If one VDEV is a mirror, all VDEVs should be mirrors. If one VDEV is a RAIDZ-1, all VDEVs should be RAIDZ-1. Unless of course, you know what you are doing, and are willing to accept the consequences. ZFS attempts to balance the data across VDEVs. Having a VDEV of a different redundancy can lead to performance issues and space efficiency concerns, and make it very difficult to recover in the event of a failure.

I am saying it is determined by your fault tolerance. How do you not get that? You guys are FAR BEYOND the point of this post. So please, stop posting shit off-topic!
Edit: I also never said that its infallible. My HGSTs barely have any hours on them. These new 1TB disks have over 20k hours each. So, i am interested in the mix of RAIDZ1 & RAIDZ2.

Your understanding of failure rates is appalling. Just because your drives are new does not ensure that they will not fail. And, as with all things, they are getting older every day. With no way to change the vDev parity level in the future, you will be the owner of an unrecommended storage pool consisting of poorly chosen vDevs. When, not if, but when that causes you grief, please do not come crying for help.

Finally, just because you do not like the answers we are providing, it does not make it ok for you to be rude. None of what was discussed here was off topic. I answered your question in the first reply to the best of my ability given the information available to me.

So build your system however you want, cause you will have to fix it when it breaks.

Regards

 

[Lastb0isct]

I think its quite rude for you to outright laugh and eye-roll in your first response without knowing my setup or needs at all. I had googled and found that article. It is over 4 years old as well. This is why i came here looking for more up-to-date advise. I am not someone that doesn't do my research before asking a question...

I have already said that the zpool is not containing any important data. I have other zpools for that.

Also, quite funny that you're using a RAIDZ1 according to your sig...yet vehemently against anyone using them. With the same size drives as me no less...

 

[depasseg]

I am curious if this is a big no-no or if it is okay?

It's normally a big no-no, but since it sounds like you aren't worried about performance or loss, then I'd say go for it.

 

[Bidule0hm]

also, i don't think your information is quite current.

You link an article from 2007 and a reddit post with 1 upvote...lol.

Yes, i did and it seems outdated.

It is over 4 years old as well. This is why i came here looking for more up-to-date advise.

Please stop saying the info is too old. If a member post a link/info then it is considered to be up-to-date whatever the date of it is.

To answer the question: what @depasseg said; it's not recommended but as you don't care about the data on this pool then do it if you want. Just don't come here and cry when your data will be lost because you've been warned more than one time it's not recommended.