From mboxrd@z Thu Jan 1 00:00:00 1970 From: Romu Hu Subject: Re: RHEL6.6 dm-cache and dm-era Date: Thu, 18 Sep 2014 16:27:41 +0800 Message-ID: <541A977D.7010108@gmail.com> References: <54164DC0.3020907@gmail.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development List-Id: dm-devel.ids On 2014/9/16 4:25, Brassow Jonathan wrote: > On Sep 14, 2014, at 9:24 PM, Romu Hu wrote: > >> Hi, >> >> According to https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6-Beta/html-single/6.6_Release_Notes/index.html#bh-storage, dm-cache and dm-era have been added into RHEL6.6 as technology preview, but I couldn't find any other documentation about using dm-cache and dm-era. I found the following utilities in >> >> /usr/sbin/era_check >> /usr/sbin/era_dump >> /usr/sbin/era_invalidate >> >> /usr/sbin/cache_check >> /usr/sbin/cache_dump >> /usr/sbin/cache_repair >> /usr/sbin/cache_restore >> >> I guess these utilities are related to dm-era and dm-cache, respectively. There are only manpages for the cache utilities. After reading the manpages I still have no clue how to use these technologies. I want to do a sanity check of these technologies on my SAN storage. Is it possible to try dm-cache and dm-era without a SSD? e.g. using ram to imitate a fast block device.. >> >> Any idea? > You can use cache to teir any block device over another. Layering faster, smaller drives over slower, larger ones is the point; but for testing non-performance things you can still do it. For the cache target, it would be a more inclusive test to go through LVM. The lvmcache.7 man page would help out with that. There is no dm-era support in LVM ATM. > > brassow Thanks, I have successfully set up LVM caching with dm-cache, works like a charm. However, I still haven't any useful documentation about how to set dm-era. Any idea? Thanks Romu