From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tomasz Torcz Subject: Re: Offline Deduplication for Btrfs Date: Thu, 6 Jan 2011 15:30:20 +0100 Message-ID: <20110106143019.GB14674@mother> References: <1294245410-4739-1-git-send-email-josef@redhat.com> <4D24AD92.4070107@bobich.net> <20110105194645.GC2562@localhost.localdomain> <4D24D8BC.90808@bobich.net> <4D251888.7060508@shiftmail.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 To: linux-btrfs@vger.kernel.org Return-path: In-Reply-To: <4D251888.7060508@shiftmail.org> List-ID: On Thu, Jan 06, 2011 at 02:19:04AM +0100, Spelic wrote: > >CPU can handle considerably more than 250 block hashings per > >second. You could argue that this changes in cases of sequential > >I/O on big files, but a 1.86GHz GHz Core2 can churn through > >111MB/s of SHA256, which even SSDs will struggle to keep up with. >=20 > A normal 1TB disk with platters can do 130MB/sec sequential, no probl= ems. > A SSD can do more like 200MB/sec write 280MB/sec read sequential or > random and is actually limited only by the SATA 3.0gbit/sec but soon > enough they will have SATA/SAS 6.0gbit/sec. By =E2=80=9Csoon enough=E2=80=9D you really meant =E2=80=9Ca year ago= =E2=80=9D, I think: http://www.anandtech.com/show/3812/the-ssd-diaries-crucials-realssd-c30= 0 Current 6Gbps SSD are doing 415 MB/s sequential: http://www.anandtech.com/show/4086/microns-realssd-c400-uses-25nm-nand-= at-161gb-offers-415mbs-reads or even claim 550MB/s: http://www.anandtech.com/show/4100/ocz-vertex-pro-3-demo-worlds-first-s= andforce-sf2000 (funny bit: Sandforce SSD controllers dedup internally).=20 Anyway, 6Gbps is not a future tale, but something long available. And not the fastest kids on the block: currently build filesystems must deal storage providing many gigabytes per second. Think of massive disk arrays or stuff like Oracle F5100, claiming 12.8GB/sec read and ~10GB/s write (in one rack unit). --=20 Tomasz Torcz "God, root, what's the difference?" xmpp: zdzichubg@chrome.pl "God is more forgiving." -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html