On 7 August 2015 at 10:47, Sjoerd <sjo...@sjomar.eu> wrote: > While we're at it: any idea why the default for SSD's is single for meta data > as described on the wiki? > (https://btrfs.wiki.kernel.org/index.php/Using_Btrfs_with_Multiple_Devices#Filesystem_creation) > > I was looking for an answer why my SSD just had single metadata, while I > expected it to be DUP and stumbled on this wiki article. Can't find a reason > for why a SSD would be different? > > Cheers, > Sjoerd
I would assume that it is because some SSD drives controllers deduplicate by default [1]. The developers probably think that when it comes to your data the truth, no mater how ugly, is preferable to a false sense of security. (Btrfs thinking it has 2 copies of metadata when the SSD drive only actually has stored 1 copy). [1] How SSDs can hose your data http://www.zdnet.com/article/how-ssds-can-hose-your-data/ "Researchers found that at least 1 Sandforce SSD controller - the SF1200 - does block-level deduplication by default. Which can be a problem. Many file systems - NTFS, most Unix/Linux FSs, ZFS are some - write critical metadata to multiple blocks in case one copy gets corrupted. But what if, unbeknownst to you, your SSD de-duplicates that block, leaving your file system with only 1 copy? " Thanks, Mike -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
