<div dir="ltr"><div><div><div>given what the drive arrays are used for, dedup is a big plus (people make copies and copies of research files like drive space is $0!). And, yeah, even with no dedup, 32G is not going to cut it anyway.<br>
<br></div>The checksums for RAID6 are the same as in raidz2. <br><br></div>I found a 250G SSD but can't use it. I have one other system I can put it on but it has not enough PCIe slots for the need. <br><br></div>the solution to all of this is $$$$$ for new system :-(<br>
</div><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Apr 19, 2013 at 11:58 AM, Derek Atkins <span dir="ltr"><<a href="mailto:warlord@mit.edu" target="_blank">warlord@mit.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Jim,<br>
<div class="im"><br>
Jim Kinney <<a href="mailto:jim.kinney@gmail.com">jim.kinney@gmail.com</a>> writes:<br>
<br>
> After much research, I have decided to NOT implement ZFS. The main factors of<br>
> interest were the raidz2 and data deduplication. In order to support the<br>
> deduplication,the server needs 5G RAM per 1TB storage. That's a deal breaker<br>
> right there as the system to be used will only support 32G and has 50TB.<br>
> Raidz2 is basically software RAID6 which I can already do.<br>
><br>
> Looked at getting an SSD for the deduplication data and using l2arc but I have<br>
> no space to install it on that server. Grr.<br>
<br>
</div>Do you really feel you need ZFS deduplication? According to<br>
<a href="http://doc.freenas.org/index.php/Hardware_Recommendations" target="_blank">http://doc.freenas.org/index.php/Hardware_Recommendations</a> you only need<br>
5GB/TB if you're using dedup. If you're just using ZFS then they<br>
recommend 1GB/TB. Granted, if you've got 50TB of data then a 32GB<br>
memory limit wont be useful to you.<br>
<br>
However, thank you for making me look at that; I was considering a<br>
32GB-limit Mobo for my system, which I was expecting to start at 12TB<br>
usable but potentially expanding to 96TB. I don't think a 96TB ZFS<br>
would work well with 32GB memory.<br>
<br>
OTOH, is ZFS really only just "RAID6"? I thought that the ZFS checksums<br>
would provide improved data integrity (scrubbing) over pure RAID6?<br>
<span class="HOEnZb"><font color="#888888"><br>
-derek<br>
</font></span><div class="HOEnZb"><div class="h5"><br>
> On Fri, Mar 29, 2013 at 3:10 PM, Ed Cashin <<a href="mailto:ecashin@noserose.net">ecashin@noserose.net</a>> wrote:<br>
><br>
> Thanks in advance for the notes you take. I'm interested to hear what you<br>
> find.<br>
><br>
> By the way, work sent me to a Nexenta course in 2010 where I learned ZFS<br>
> stuff from Richard Elling:<br>
><br>
> <a href="http://www.richardelling.com/" target="_blank">http://www.richardelling.com/</a><br>
><br>
> ... and one thing that kept coming up is how users usually reach for the<br>
> RAID-Z options when stripes of mirrors would perform better and offer more<br>
> flexibility. I thought that was notable.<br>
><br>
> On Fri, Mar 29, 2013 at 2:44 PM, Jim Kinney <<a href="mailto:jim.kinney@gmail.com">jim.kinney@gmail.com</a>> wrote:<br>
><br>
> There was an update to this that just hit /.<br>
><br>
> WooHoo!<br>
><br>
> I have not used ZFS (minimal solaris experience) before but I have a<br>
> situation where raidz looks like a very good choice. An external 16<br>
> bay JBOD box hanging off a SAS HBA looks like a prime candidate. The<br>
> big issue for me is the support for native NFSv4 ACLs which solves<br>
> some issues.<br>
><br>
> As I go through this exercise, I'll keep some notes and maybe look at<br>
> a presentation on doing this.<br>
><br>
> hints, gotcha's, are very welcome.<br>
><br>
> I did find a pdf of the zfsadmin.pdf <a href="http://pdfhome.org/zfsadmin.pdf" target="_blank">http://pdfhome.org/zfsadmin.pdf</a><br>
><br>
> --<br>
> --<br>
> James P. Kinney III<br>
><br>
> Every time you stop a school, you will have to build a jail. What you<br>
> gain at one end you lose at the other. It's like feeding a dog on his<br>
> own tail. It won't fatten the dog.<br>
> - Speech 11/23/1900 Mark Twain<br>
><br>
> <a href="http://electjimkinney.org" target="_blank">http://electjimkinney.org</a><br>
> <a href="http://heretothereideas.blogspot.com/" target="_blank">http://heretothereideas.blogspot.com/</a><br>
><br>
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> --<br>
> --<br>
> James P. Kinney III<br>
><br>
> Every time you stop a school, you will have to build a jail. What you gain at<br>
> one end you lose at the other. It's like feeding a dog on his own tail. It<br>
> won't fatten the dog.<br>
> - Speech 11/23/1900 Mark Twain<br>
><br>
> <a href="http://electjimkinney.org" target="_blank">http://electjimkinney.org</a><br>
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><br>
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<br>
--<br>
</div></div><div class="im HOEnZb"> Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory<br>
Member, MIT Student Information Processing Board (SIPB)<br>
URL: <a href="http://web.mit.edu/warlord/" target="_blank">http://web.mit.edu/warlord/</a> PP-ASEL-IA N1NWH<br>
<a href="mailto:warlord@MIT.EDU">warlord@MIT.EDU</a> PGP key available<br>
<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>-- <br>James P. Kinney III<br><i><i><i><i><br></i></i></i></i>Every time you stop a school, you will have to build a jail. What you
gain at one end you lose at the other. It's like feeding a dog on his
own tail. It won't fatten the dog.<br>
- Speech 11/23/1900 Mark Twain<br><i><i><i><i><br><a href="http://electjimkinney.org" target="_blank">http://electjimkinney.org</a><br><a href="http://heretothereideas.blogspot.com/" target="_blank">http://heretothereideas.blogspot.com/</a><br>
</i></i></i></i>
</div>