Date: Fri, 14 Dec 2007 19:02:12 -0800 From: Maxim Sobolev <sobomax@FreeBSD.org> To: Ivan Voras <ivoras@FreeBSD.org> Cc: freebsd-current@FreeBSD.org Subject: Re: ZFS melting under postgres... Message-ID: <476343B4.8080208@FreeBSD.org> In-Reply-To: <fjuljp$cvb$1@ger.gmane.org> References: <47606C09.2070209@isc.org> <47609F0A.7010805@clearchain.com> <47609FE3.8040606@barafranca.com> <4760B444.1080604@clearchain.com> <06CAC7FC-DB58-441D-A6E0-76D1D8133393@tamu.edu> <86ir31xwlu.fsf@ds4.des.no> <ADCCD5E6-A792-49B9-A346-753176C12F2E@tamu.edu> <fjuljp$cvb$1@ger.gmane.org>
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Ivan Voras wrote: > David Duchscher wrote: >> On Dec 14, 2007, at 6:57 AM, Dag-Erling Smørgrav wrote: >> >>> David Duchscher <daved@tamu.edu> writes: >>>> So does anybody know of a battery backed NVRAM card that can be used >>>> with FreeBSD that the ZIL could be offloaded to? >>> Any CF card or similar will do. You don't need battery backup for >>> flash memory. >> I did think of that but is a CF card faster than a good SAS or SATA >> drive? > > Not in transfer rate, but it could help hugely with seek-intensive IO > loads (since seeks are instantaneous on flash or other solid-state > drives). In theory, they could be of immense benefit for databases and > seek-intensive operations on file systems, but the limited bulk transfer > rates and relatively small sizes (for decent money) currently prevent > their wide-spread use. That's no longer true. You can't get more than 5-10MB/s from seek-intensive RAID0 with two 15K drives, while 20-30MB/s is not a problem for the comparable priced/sized SSD drive. -Maxim
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