`<div dir="ltr">I have found that turning on compression gets more savings when storing my backups then I got with dedup on. I run gzip-9 for my backup dataset. I think dedup is good if you are storing a lot of files that really are the same. Your mileage may vary compared to mine. I do a full backup once a week and incrementals daily.</div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Dec 15, 2014 at 2:17 PM, Rune Tipsmark <span dir="ltr"><<a href="mailto:rt@steait.net" target="_blank">rt@steait.net</a>></span> wrote:<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">we have only 24GB of ram on this system...<br>
I was under the impression it would not require much when the block size was larger, we are on 64kb, so would expect around 2GB per 1TB.<br>
yet we cannot even get more than a few TB on the system before it dies.<br>
<br>
the main purpose with this system was dedup, no problem with slow speed... its for backup only, so could not care less if its rather slow - but not responding is not acceptable.<br>
br,<br>
Rune<br>
________________________________________<br>
From: OmniOS-discuss <<a href="mailto:omnios-discuss-bounces@lists.omniti.com">omnios-discuss-bounces@lists.omniti.com</a>> on behalf of Dominik Hassler <<a href="mailto:hasslerd@gmx.li">hasslerd@gmx.li</a>><br>
Sent: Monday, December 15, 2014 10:11 PM<br>
To: <a href="mailto:omnios-discuss@lists.omniti.com">omnios-discuss@lists.omniti.com</a><br>
Subject: Re: [OmniOS-discuss] dedup causes zfs/omnios to drop connections.<br>
<div class="HOEnZb"><div class="h5"><br>
Hi,<br>
<br>
we used dedup on a production machine w/ 256 GB RAM, but disabled it<br>
after a couple of days due to huge performance impact.<br>
<br>
I would not recommend to use dedup even when having "enough" RAM.<br>
<br>
On 12/15/2014 09:53 PM, Dan McDonald wrote:<br>
><br>
>> On Dec 15, 2014, at 3:43 PM, Rune Tipsmark <<a href="mailto:rt@steait.net">rt@steait.net</a>> wrote:<br>
>><br>
>> hi all,<br>
>><br>
>> got a new system I was intending on using as backup repository. Whenever dedup is enabled it dies after anywhere between 5 and 30 minutes. I need to reboot OmniOS to get it back online.<br>
>> the files being copied onto the zfs vols are rather large, about ~2TB each... if I copy smaller files, say 400GB or so, it takes longer for it to crash.<br>
>><br>
>> what can be done to fix this? after Windows (initiator) looses the connection (both Fibre Channel and iSCSI) I still see a lot of disk activity using iostat - disks remain active for minutes after the copying has died... its like ZFS cannot handle dedup of large files..<br>
><br>
> Dedup is a memory pig and not very well implemented in ZFS. I'd highly recommend against it in production. Either that, or really increase your memory for your system in question. There was some work going on at Nexenta to perhaps put the dedup tables (DDTs) onto a dedicated slog-like device, but I believe that work stalled.<br>
><br>
> Sorry,<br>
> Dan<br>
><br>
><br>
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</div></div></blockquote></div><br clear="all"><div><br></div>-- <br><div class="gmail_signature">Jason Cox</div>
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