On Tue, Mar 17, 2020 at 1:59 AM <tu...@posteo.de> wrote: > > The HD will contain the whole system including the complete root > filesustem. Updateing, installing via Gentoo tools will run using > the HD. If that process has ended, I will rsync the HD based root > fileystem to the SSD. > ...
I'll go ahead and write one consolidated reply to a couple of points raised in these two threads to save everybody emails. First, I'll echo what was said about this being probably an overly-complex solution to the problem. I think you'll spend more time dealing with this than with any SSD failure issues. Next, in general you tend to get what you pay for. With SSDs if you're getting that bargain 512GB drive for $15 when all the comparable drives are $70, and it was made by some company you've never heard of, chances are that you're missing something. I'm not saying you need to go buy that 150% more expensive "signature edition" drive or whatever, though it might very well have some feature that justifies its price. Just be wary if things that look too good to be true. If you buy a reputable brand that is marketed for your intended use chances are you're getting something decent, even if you're paying 10% more. If you really know what you're doing you can certainly use research to save money by critically evaluating your options. Finally, ALL DRIVES FAIL. It doesn't matter what the underlying storage technology is. I've seen hard drives fail in less than a year, with the warranty replacement drive failing less than a year after that. I think next warranty replacement (still in the original warranty period) lasted 5+ years of near-continuous use. The typical failure modes of hard drives and solid state storage are different, but they all fail. You can't perfectly predict WHEN they will fail either. Most drives have SMART and sometimes it can detect failure conditions before failure, but not always. What will you do when your brand new drive fails 3 weeks after you buy it? If you don't have an answer that doesn't involve you losing stuff you don't want to lose, or having downtime you don't want to have, then you need to re-evaluate your approach. Backups and RAID are the obvious solutions - with backup generally being the more reliable solution to data loss, and RAID being the more reliable solution to downtime, but with them both having some overlap. Here is what I've done: 1. Preferred solution to SSD failure and associated downtime is RAID+backups. The most important stuff is backed up to the cloud, encrypted. With SSDs I usually do a full backup to hard drives since that is fairly inexpensive given their relative capacities. I'm using ZFS mirroring as my RAID-like solution right now, and I use ZFS-send/receive to do hourly backups that are very low overhead. 2. If I'm too cheap to use RAID on a host then I just do the hourly ZFS remote snapshots - that is a good solution on hosts where downtime doesn't matter, because I can just get a new drive and restore the snapshot and I'm back in business after a day or two, accepting a one hour recovery point objective. You can of course use rsync as well. For rsync-based backups I recommend rsnapshot, in portage. For zfs remote snapshots I have switched to zfs_autobackup: https://github.com/psy0rz/zfs_autobackup/blob/master/README.md -- Rich
