From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter J Braam Date: Thu, 24 Jan 2008 17:08:17 +0800 Subject: [Lustre-devel] flash cache page In-Reply-To: <1201135464.14768.13.camel@linux.site> References: <478E29FF.2050306@sun.com> <478E52AE.4060801@sun.com> <1200609618.30173.3.camel@linux.site> <47968E73.9020401@sun.com> <1201135464.14768.13.camel@linux.site> Message-ID: <47985581.1070702@sun.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lustre-devel@lists.lustre.org >> 1 Use case table. >> >> i. we decided on an implementation constraint to store both file layouts >> as attributes of objects in a redirection layer in the client. These >> layouts would be obtained from the MDS cluster, see (iv) >> >> ii. We decided that locks would be taken in a hierarchical manner - >> the flash cache would run a LDLM and locks would be taken there. >> >> iii. Correctness would be handled automatically through the >> hierarchy. >> > > > >> However, to avoid a lot of reading "write only locks" used >> when entire pages are written are probably desirable (i.e. the caching >> infrastructure on the flash OST's is different from a Lustre client). >> >> > > If a client writes a full page, the page should not first be read by the flash cache. Almost too obvious perhaps. - Peter -