Date: Fri, 14 Dec 2007 20:29:56 +0100 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-current@freebsd.org Subject: Re: ZFS melting under postgres... Message-ID: <fjuljp$cvb$1@ger.gmane.org> In-Reply-To: <ADCCD5E6-A792-49B9-A346-753176C12F2E@tamu.edu> 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>
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This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig1A1DEE1A2CE5DCBF3237FE53 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable David Duchscher wrote: > On Dec 14, 2007, at 6:57 AM, Dag-Erling Sm=C3=B8rgrav wrote: >=20 >> 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. >=20 > I did think of that but is a CF card faster than a good SAS or SATA > drive?=20 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. It would be logical to use a limited size SSD for something like a file system journal for a large file system, except that these kind of journals are usually not seek-intensive :) > Fastest ones I found have a top rating of 45MB/s. The one > battery backed NVARM card that showed up in a google search had a peak > rate of 533MB/s. The question seems moot though since FreeBSD doesn't > currently support them. If a NVRAM or SSD, or other technology presents the drive as a (S)ATA drive, there's no reason it shouldn't. --------------enig1A1DEE1A2CE5DCBF3237FE53 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFHYtm5ldnAQVacBcgRAuFqAKCMNnIyN55dgZ8C8SYfXPuTHAEUGACgyh4l 9zh8woR+VEufqAF8aCLjQik= =S9hA -----END PGP SIGNATURE----- --------------enig1A1DEE1A2CE5DCBF3237FE53--
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