Return-Path: Delivered-To: apmail-cassandra-user-archive@www.apache.org Received: (qmail 18387 invoked from network); 8 Mar 2011 18:25:18 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (140.211.11.3) by minotaur.apache.org with SMTP; 8 Mar 2011 18:25:18 -0000 Received: (qmail 6532 invoked by uid 500); 8 Mar 2011 17:23:16 -0000 Delivered-To: apmail-cassandra-user-archive@cassandra.apache.org Received: (qmail 6503 invoked by uid 500); 8 Mar 2011 17:23:16 -0000 Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@cassandra.apache.org Delivered-To: mailing list user@cassandra.apache.org Received: (qmail 6494 invoked by uid 99); 8 Mar 2011 17:23:16 -0000 Received: from nike.apache.org (HELO nike.apache.org) (192.87.106.230) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 08 Mar 2011 17:23:16 +0000 X-ASF-Spam-Status: No, hits=-0.7 required=5.0 tests=RCVD_IN_DNSWL_LOW,SPF_PASS X-Spam-Check-By: apache.org Received-SPF: pass (nike.apache.org: domain of rcoli@digg.com designates 209.85.210.172 as permitted sender) Received: from [209.85.210.172] (HELO mail-iy0-f172.google.com) (209.85.210.172) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 08 Mar 2011 17:23:10 +0000 Received: by iyj8 with SMTP id 8so6292788iyj.31 for ; Tue, 08 Mar 2011 09:22:49 -0800 (PST) MIME-Version: 1.0 Received: by 10.231.113.227 with SMTP id b35mr4154728ibq.36.1299604968996; Tue, 08 Mar 2011 09:22:48 -0800 (PST) Received: by 10.231.185.81 with HTTP; Tue, 8 Mar 2011 09:22:48 -0800 (PST) In-Reply-To: References: <5FAFCB6230A1754CBC58296E62D8D5E602E89EECD7@pa-ex-01.YOJOE.local> Date: Tue, 8 Mar 2011 09:22:48 -0800 Message-ID: Subject: Re: when do snapshots go away? From: Robert Coli To: user@cassandra.apache.org Content-Type: text/plain; charset=ISO-8859-1 X-Virus-Checked: Checked by ClamAV on apache.org On Tue, Mar 8, 2011 at 1:25 AM, Sylvain Lebresne wrote: > And it's far easier for you to know what to do with the snapshot > (whether that is deleting it or archiving it somewhere) than for the > application. Snapshots also have the neat property of not being the full size of your corpus unless you are always major compacting, because they are hard links. This can be confusing if you use "du" to check the sizes of your snapshots to see if they're consistent, because du only counts disk usage the first time it sees a hard link. It is somewhat counter-intuitive that snapshots effectively get larger over time as they become the only copy of that version of the sstable on disk, when the "original" sstable is deleted via compaction. =Rob