From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Brown Subject: Re: SSD - TRIM command Date: Wed, 09 Feb 2011 16:49:40 +0100 Message-ID: References: <4D517F4F.4060003@gmail.com> <4D5245DF.4020401@hardwarefreak.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids On 09/02/2011 15:39, Roberto Spadim wrote: > guys... > if my ssd fail, i buy another... > let's make software ok, the hardware is another problem > raid1 should work with floppy disks, hard disks, ssd, nbd... that's the point > make solutions for hardware mix > the question is simple, could we send TRIM command to all mirrors (for > stripe just disks that should receive it)? if device don't have TRIM > we should translate it for a similar command, with the same READ > effect (no problem if it's not atomic) > I've been reading a little more about this. It seems that the days of TRIM may well be numbered - the latest generation of high-end SSDs have more powerful garbage collection algorithms, together with more spare blocks, making TRIM pretty much redundant. This is, of course, the most convenient solution for everyone (as long as it doesn't cost too much!). The point of the TRIM command is to tell the SSD that a particular block is no longer being used, so that the SSD can erase it in the background - that way when you want to write more data, there are more free blocks ready and waiting. But if you've got plenty of spare blocks, it's easy to have them erased in advance and you don't need TRIM.