Community Edition 16TB Limit

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Re: Community Edition 16TB Limit

Post by audiophil » Sun Sep 30, 2012 9:52 pm

mkush wrote:audiophil, is there any way you could test a single pool that has (1) more than 16TB physical storage but (2) less than 16TB actual storage due to RAIDZ/Z2 loss... This is the particular case I need to know about.


I'll try 9x2TB when time permits. Have to shuffle some data around first.
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Re: Community Edition 16TB Limit

Post by dbrady » Sun Sep 30, 2012 10:08 pm

The current 16TB limit is for the total pool storage size not including spares, logs and cache devices. This pool size property can be seen in a zpool list command or a zpool get.

Code: Select all
$ zpool get size tank
NAME    PROPERTY  VALUE   SOURCE
tank    size      16Ti    -
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Re: Community Edition 16TB Limit

Post by audiophil » Sun Sep 30, 2012 10:44 pm

Well that answers that :)
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(7082249) (6948890) potential issues with import, maybe OT

Post by grahamperrin » Sun Sep 30, 2012 11:48 pm

audiophil wrote:… 3 different pools exceeding 16TB in total disks …


I wonder what would happen with an import to ZEVO from a single pool exceeding 16 TB where the actual size used is less than 16 TB.

Maybe off-topic, from around a year ago, this caught my eye:

Re: [zfs-discuss] zpool import starves machine of memory, later given an Oracle CR#7082249 and marked as a duplicate of CR# 6948890 … but (sorry) I don't know whether any parts of Oracle's bug tracking systems are open for things such as that.

No idea how the patch mentioned on 2011-08-24 relates to the code base(s) for ZEVO.

PS sorry, crossed paths with Don's post.
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Re: Community Edition 16TB Limit

Post by mkush » Mon Oct 01, 2012 12:13 am

audiophil, never mind the test, doesn't seem necessary. Per Don's remarks in the edit to your original post, it seems that it is the total size of the disks in the pool. I verified by running that command on my OpenIndiana box, 8x 4TB drives, and it reports a size of 29TB (in essence the ~32TB raw size you'd expect from the drives, not the ~24TB of actual usable space due to RAIDZ2). Bad news!
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Re: Community Edition 16TB Limit

Post by mikearma10 » Thu Oct 18, 2012 7:13 am

I have an 18tb Pool that is RaidZ1... so 20tb of formatted space, but 18tb usable due to RaidZ1... When I plug into ZEVO it limits to 16tb, not 14tb, so your answer is... the limit is most likely based on the usable pool storage area, rather than total storage space :)

Which is a good thing!
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Re: Community Edition 16TB Limit

Post by si-ghan-bi » Thu Oct 18, 2012 8:41 am

You have a 10x2TB array in RAIDZ1?
You may read this:
http://www.zdnet.com/blog/storage/why-r ... n-2009/162
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Re: Community Edition 16TB Limit

Post by mikearma10 » Thu Oct 18, 2012 9:01 am

i don't have all my drives on a single VDEV for that raid... so i don't have that issue... furthermore... that issue described at zdnet has sooo many holes...

Yes re-build times are getting larger and larger, and as zfs isn't as "data-aware" as say a drobo, you require a lot of IOPS to perform a resilver... it can take hours.

However... encountering an unrecoverable read error during the re-silver can be greatly reduced without sacrificing capacity... My personal view is the opposite of what people say is a good idea... I think you should buy drives from different vendors, with non-sequential serial numbers and install them... Giving that, your failure rate should be variable amoung your pool. Also, be smart.. keep an eye on your SMART stats.. if things are going high. prepare for a failure.
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Re: Community Edition 16TB Limit

Post by grahamperrin » Thu Oct 18, 2012 9:35 am

si-ghan-bi wrote:You have a 10x2TB array in RAIDZ1?
You may read this:
http://www.zdnet.com/blog/storage/why-r ... n-2009/162


Thanks – leaves me wondering … RAID-Z, scrub and probabilities of reconstruction failure
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Re: Community Edition 16TB Limit

Post by daniel.jozsef » Mon Oct 29, 2012 9:17 pm

To me it seemed that ZEVO has been sort of "dropped", with the for-pay version discontinued, and the whole thing thrown out into the open source world as the community edition.
If I was mistaken and Greenbytes will actually put effort into ZFS, that sounda pretty cool... But I wonder, is that a fact, or only wishful thinking?
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