Date: Sun, 21 Sep 2014 16:42:26 +0800 From: Xin Li <delphij@delphij.net> To: Matthias Andree <matthias.andree@gmx.de>, freebsd-scsi@freebsd.org Subject: Re: How to disable hard disk write cache? Message-ID: <541E8F72.4020202@delphij.net> In-Reply-To: <541E8DAE.8010407@gmx.de> References: <541804B0.7070407@gmail.com> <54184484.1070304@delphij.net> <541E8DAE.8010407@gmx.de>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 9/21/14 4:34 PM, Matthias Andree wrote: > Am 16.09.2014 um 16:09 schrieb Xin Li: > >> Modern SATA/SAS/SCSI devices usually comes with the capability >> of tagged commands, allowing the OS to know when a write buffer >> is on stable storage. With this, file systems can easily >> implement the right semantics and recover from e.g. a power >> outage, etc. > > Yes, they *can easily implement* that, but which file systems in > FreeBSD *actually do* that? Both UFS (with Soft Updates, which is what it's all about; I haven't checked the Journalled Soft Updates case) and ZFS do that for ages. Cheers, -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJUHo9xAAoJEJW2GBstM+nsMo0P/2oyyJeH0LOvGGMIDJWw4CZf WGbEcecdQ3idVAw/2j/aYrlGpeYpGNZWi7dv5MOc3jdWRQbGkZ5r3E90YaSiwLac CRix+ovXeM+g7KSfb4q5NNrn9SEpQe8AklS5deTiFP3JxfV4juAf/aXUoCtrpdhm acVh0jYpel5ffdKDzXrHpKItvZ7t0YBg2qATK83+TGJ5cdefcEQnvKnOBMShyM4U ReOoeFO1y8ZBh9aVSYJlMarghxVXar212MavvLJxvKruQE++xf2lnhf8BkvCRiSd Xz24LZMJ/Cz92jMuYbCQ7sX4iIDkcCzpZeVOO8NjBE4YCc5XOCeIvw4uUdLwuWEz QqLLZYbepN1cjPraSrmNH8wFA6kZIQuZvMb3JJt6zRR8621VDg2IABAA4KyKs9CB 74shN5alKNCiDNf75EXfcZL30lTx8KDf/dPAil/mtYc0s7Orwc6veRDVmshCvSH+ y+f5NMYyOuVVoSrGNIhdP21c7vRyAywUVKgBT7IbnZg8I5ORNumCNcSFt+Q8c9Az sIC2cR2XVqCRQpH7qnfoot1e0FwUJEdyOHupVVMlTzFb55z06k79/w1/rruY4ylT rSunaKPy5xm4e43JxgzNhXobH6Qd0qO9VxB5nNb4By52GDccS5xIQw6v36TVXorn WfdQb0tZYKfnlE8tjCKH =MkPK -----END PGP SIGNATURE-----
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