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.
On Mon, Dec 15, 2014 at 2:17 PM, Rune Tipsmark <[email protected]> wrote: > > we have only 24GB of ram on this system... > 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. > yet we cannot even get more than a few TB on the system before it dies. > > 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, > Rune > ________________________________________ > From: OmniOS-discuss <[email protected]> on behalf > of Dominik Hassler <[email protected]> > Sent: Monday, December 15, 2014 10:11 PM > To: [email protected] > Subject: Re: [OmniOS-discuss] dedup causes zfs/omnios to drop connections. > > Hi, > > we used dedup on a production machine w/ 256 GB RAM, but disabled it > after a couple of days due to huge performance impact. > > I would not recommend to use dedup even when having "enough" RAM. > > On 12/15/2014 09:53 PM, Dan McDonald wrote: > > > >> On Dec 15, 2014, at 3:43 PM, Rune Tipsmark <[email protected]> wrote: > >> > >> hi all, > >> > >> 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. > >> 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. > >> > >> 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.. > > > > 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. > > > > Sorry, > > Dan > > > > > > _______________________________________________ > > OmniOS-discuss mailing list > > [email protected] > > http://lists.omniti.com/mailman/listinfo/omnios-discuss > > > _______________________________________________ > OmniOS-discuss mailing list > [email protected] > http://lists.omniti.com/mailman/listinfo/omnios-discuss > -- Jason Cox
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