Re: Write cache for a SAN

From: Svetoslav Gyurov <>
Date: Mon, 03 Nov 2008 17:17:43 +0200
Message-ID: <>



No we do not disable it, in particular depending of the model, the EVA (Enterprise Virtual Array, which is mid-range storage from HP) has two controllers, each has a 1, 2 or 4 Gb cache which is shared between policy, read, write and mirror cache. Each controller has hot plug cache batteries (1 or 2, depends on the model) to maintain cache contents for up to 96 hours in case of a total power failure and/or inappropriate shutdown. After this time (maybe less) the information in the cache is lost and virtual disks are marked as broken because they are no more consistent.


Jeffrey Beckstrom wrote:
For those of you using a SAN, do you disable the write cache?  I am concerned that if the UPS loses power thus bringing the SAN down,that writes to the datafiles would be lost.  Oracle would think they are completed but never actually done.
Jeffrey Beckstrom
Database Administrator
Greater Cleveland Regional Transit Authority
1240 W. 6th Street
Cleveland, Ohio 44113

-- Received on Mon Nov 03 2008 - 09:17:43 CST

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