From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: Ext4 and xfs problems in dm-thin on allocation and discard Date: Tue, 19 Jun 2012 09:23:33 -0500 Message-ID: <4FE08B65.70303@redhat.com> References: <4FDF9EBE.2030809@shiftmail.org> <20120619141933.GC10637@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20120619141933.GC10637@thunk.org> Sender: linux-ext4-owner@vger.kernel.org To: Ted Ts'o Cc: =?UTF-8?B?THVrw6HFoSBDemVybmVy?= , Spelic , xfs@oss.sgi.com, linux-ext4@vger.kernel.org, device-mapper development List-Id: dm-devel.ids On 6/19/12 9:19 AM, Ted Ts'o wrote: > On Tue, Jun 19, 2012 at 04:09:48PM +0200, Luk=C3=A1=C5=A1 Czerner wro= te: >> >> With thin provisioning you'll get totally different file system >> layout than on fully provisioned disk as you push more and more >> writes to your drive. This unfortunately has great impact on >> performance since file systems usually have a lot of optimization on >> where to put data/metadata on the drive and how to read them. >> However in case of thinly provisioned storage those optimization >> would not help. And yes, you just have to expect lower performance >> with dm-thin from the file system on top of it. It is not and it >> will never be ideal solution for workloads where you expect the best >> performance. >=20 > One of the things which would be nice to be able to easily set up is = a > configuration where we get the benefits of thin provisioning with > respect to snapshost, but where the underlying block device used by > the file system is contiguous. That is, it would be really useful to > *not* use thin provisioning for the underlying file system, but to us= e > thin provisioned snapshots. That way we only pay the thinp > performance penalty for the snapshots, and not for normal file system > operations. This is something that would be very useful both for ext= 4 > and xfs. I agree, and have asked for exactly the same thing... though I have no idea how hard it is to disentangle allocation-aware snapshots from thin= g provisioned storage. -Eric -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q5JENjUe103304 for ; Tue, 19 Jun 2012 09:23:46 -0500 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id ahO6r71OKeAEwERj for ; Tue, 19 Jun 2012 07:23:44 -0700 (PDT) Message-ID: <4FE08B65.70303@redhat.com> Date: Tue, 19 Jun 2012 09:23:33 -0500 From: Eric Sandeen MIME-Version: 1.0 Subject: Re: Ext4 and xfs problems in dm-thin on allocation and discard References: <4FDF9EBE.2030809@shiftmail.org> <20120619141933.GC10637@thunk.org> In-Reply-To: <20120619141933.GC10637@thunk.org> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Ted Ts'o Cc: =?UTF-8?B?THVrw6HFoSBDemVybmVy?= , linux-ext4@vger.kernel.org, xfs@oss.sgi.com, device-mapper development , Spelic T24gNi8xOS8xMiA5OjE5IEFNLCBUZWQgVHMnbyB3cm90ZToKPiBPbiBUdWUsIEp1biAxOSwgMjAx MiBhdCAwNDowOTo0OFBNICswMjAwLCBMdWvDocWhIEN6ZXJuZXIgd3JvdGU6Cj4+Cj4+IFdpdGgg dGhpbiBwcm92aXNpb25pbmcgeW91J2xsIGdldCB0b3RhbGx5IGRpZmZlcmVudCBmaWxlIHN5c3Rl bQo+PiBsYXlvdXQgdGhhbiBvbiBmdWxseSBwcm92aXNpb25lZCBkaXNrIGFzIHlvdSBwdXNoIG1v cmUgYW5kIG1vcmUKPj4gd3JpdGVzIHRvIHlvdXIgZHJpdmUuIFRoaXMgdW5mb3J0dW5hdGVseSBo YXMgZ3JlYXQgaW1wYWN0IG9uCj4+IHBlcmZvcm1hbmNlIHNpbmNlIGZpbGUgc3lzdGVtcyB1c3Vh bGx5IGhhdmUgYSBsb3Qgb2Ygb3B0aW1pemF0aW9uIG9uCj4+IHdoZXJlIHRvIHB1dCBkYXRhL21l dGFkYXRhIG9uIHRoZSBkcml2ZSBhbmQgaG93IHRvIHJlYWQgdGhlbS4KPj4gSG93ZXZlciBpbiBj YXNlIG9mIHRoaW5seSBwcm92aXNpb25lZCBzdG9yYWdlIHRob3NlIG9wdGltaXphdGlvbgo+PiB3 b3VsZCBub3QgaGVscC4gQW5kIHllcywgeW91IGp1c3QgaGF2ZSB0byBleHBlY3QgbG93ZXIgcGVy Zm9ybWFuY2UKPj4gd2l0aCBkbS10aGluIGZyb20gdGhlIGZpbGUgc3lzdGVtIG9uIHRvcCBvZiBp dC4gSXQgaXMgbm90IGFuZCBpdAo+PiB3aWxsIG5ldmVyIGJlIGlkZWFsIHNvbHV0aW9uIGZvciB3 b3JrbG9hZHMgd2hlcmUgeW91IGV4cGVjdCB0aGUgYmVzdAo+PiBwZXJmb3JtYW5jZS4KPiAKPiBP bmUgb2YgdGhlIHRoaW5ncyB3aGljaCB3b3VsZCBiZSBuaWNlIHRvIGJlIGFibGUgdG8gZWFzaWx5 IHNldCB1cCBpcyBhCj4gY29uZmlndXJhdGlvbiB3aGVyZSB3ZSBnZXQgdGhlIGJlbmVmaXRzIG9m IHRoaW4gcHJvdmlzaW9uaW5nIHdpdGgKPiByZXNwZWN0IHRvIHNuYXBzaG9zdCwgYnV0IHdoZXJl IHRoZSB1bmRlcmx5aW5nIGJsb2NrIGRldmljZSB1c2VkIGJ5Cj4gdGhlIGZpbGUgc3lzdGVtIGlz IGNvbnRpZ3VvdXMuICBUaGF0IGlzLCBpdCB3b3VsZCBiZSByZWFsbHkgdXNlZnVsIHRvCj4gKm5v dCogdXNlIHRoaW4gcHJvdmlzaW9uaW5nIGZvciB0aGUgdW5kZXJseWluZyBmaWxlIHN5c3RlbSwg YnV0IHRvIHVzZQo+IHRoaW4gcHJvdmlzaW9uZWQgc25hcHNob3RzLiAgVGhhdCB3YXkgd2Ugb25s eSBwYXkgdGhlIHRoaW5wCj4gcGVyZm9ybWFuY2UgcGVuYWx0eSBmb3IgdGhlIHNuYXBzaG90cywg YW5kIG5vdCBmb3Igbm9ybWFsIGZpbGUgc3lzdGVtCj4gb3BlcmF0aW9ucy4gIFRoaXMgaXMgc29t ZXRoaW5nIHRoYXQgd291bGQgYmUgdmVyeSB1c2VmdWwgYm90aCBmb3IgZXh0NAo+IGFuZCB4ZnMu CgpJIGFncmVlLCBhbmQgaGF2ZSBhc2tlZCBmb3IgZXhhY3RseSB0aGUgc2FtZSB0aGluZy4uLiB0 aG91Z2ggSSBoYXZlIG5vCmlkZWEgaG93IGhhcmQgaXQgaXMgdG8gZGlzZW50YW5nbGUgYWxsb2Nh dGlvbi1hd2FyZSBzbmFwc2hvdHMgZnJvbSB0aGluZwpwcm92aXNpb25lZCBzdG9yYWdlLgoKLUVy aWMKCl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCnhmcyBt YWlsaW5nIGxpc3QKeGZzQG9zcy5zZ2kuY29tCmh0dHA6Ly9vc3Muc2dpLmNvbS9tYWlsbWFuL2xp c3RpbmZvL3hmcwo=