{"id":127,"date":"2008-11-10T13:13:26","date_gmt":"2008-11-10T13:13:26","guid":{"rendered":"https:\/\/www.bishnet.net\/tim\/blog\/?p=127"},"modified":"2010-11-11T13:01:41","modified_gmt":"2010-11-11T13:01:41","slug":"freebsd-filesystem-snapshots","status":"publish","type":"post","link":"https:\/\/www.bishnet.net\/tim\/blog\/2008\/11\/10\/freebsd-filesystem-snapshots\/","title":{"rendered":"FreeBSD filesystem snapshots"},"content":{"rendered":"

I’ve been looking at filesystem snapshots<\/a> on FreeBSD lately and I have to say I wasn’t too impressed. Yes, the functionality is there, but the interface sucks. For UFS you have to create a snapshot, which takes a while, and which appears as a file within the filesystem you’re snapshotting. Then you have to use an md device to mount it. ZFS is easier, but different. What we need is a simple and standard interface to both.<\/p>\n

Fortunately I discovered Ralf Engelschall’s snapshot management utilities<\/a>. He’s written a couple of tools that make creating and managing snapshots really easy.<\/p>\n

Using cron one can schedule creation of hourly, daily and weekly snapshots for filesystems. You can specify that you want 3 hourly snapshots, 2 daily and 1 weekly for a given filesystem. The system takes care of everything else. And by using amd (the FreeBSD automounter) these snapshots can automatically be made available through a given mount point. It couldn’t get any easier!<\/p>\n

Well, actually, it could get slightly easier. Currently these tools are available from Ralf’s site or from the FreeBSD ports collection<\/a>. It strikes me that something as useful and fundamental as this should really make its way in to the base system.<\/p>\n

Update:<\/strong> Whilst this worked well in testing, once I applied it to my server with a large (approx, but not over, 2TB) filesystem it hung the machine completely, even on the console. I haven’t investigated further yet.<\/p>\n

Update 2:<\/strong> Well, I have to say I’m disappointed. Ralf’s scripts worked great, but the snapshotting of large UFS filesystems in FreeBSD is as good as broken. When it takes hours to create a snapshot, locking out the filesystem (and maybe even the machine<\/a>) for hours, it might as well not be there. There seems to be an attitude of “just accept it”, which I’m not impressed about either. Roll on ZFS… (yes – I know it’s there now, but I’d like it to mature just a little more \ud83d\ude42 ).<\/p>\n","protected":false},"excerpt":{"rendered":"

Being able to take snapshots of a filesystem is very handy for backups, but does it actually work on FreeBSD?<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,4],"tags":[140,40,41,42],"class_list":["post-127","post","type-post","status-publish","format-standard","hentry","category-computing","category-freebsd","tag-freebsd","tag-snapshot","tag-ufs","tag-zfs"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t