Michael wrote: > On Friday 15 November 2024 11:59:34 GMT Dale wrote: >> Michael wrote: >>> On Friday 15 November 2024 05:53:53 GMT Dale wrote: >>>> The thing about my data, it's mostly large video files. If I were >>>> storing documents or something, then SSD or something would be a good >>>> option. Plus, I mostly write once, then it either sits there a while or >>>> gets read on occasion. >>> For a write once - read often use case, the SMR drives are a good >>> solution. >>> They were designed for this purpose. Because of their shingled layers >>> they >>> provide higher storage density than comparable CMR drives. >> True but I don't like when I'm told a write is done, it kinda isn't. I >> recall a while back I reorganized some stuff, mostly renamed directories >> but also moved some files. Some were Youtube videos. It took about 30 >> minutes to update the data on the SMR backup drive. The part I see >> anyway. > Right there is your problem, "... SMR backup drive". SMRs are best suited to > sequential writes. With repeat random writes they go into a > read-modify-write > cycle and slow down. > > Consequently, they are well suited to storage of media files, archiving data > long term and such write-once read-often applications. They are not suited > to > heavy transactional loads and frequently overwritten data. >
All true. This was mentioned by Rich I think way back when I started a thread about this drive constantly bumping. I feel the heads moving is what the bump is. Until then, I had no idea it was a SMR drive. I'd never heard of them before. >> It sat there for a hour at least doing that bumpy thing before >> it finally finished. I realize if I just turn the drive off, the data >> is still there. Still, I don't like it appearing to be done when it >> really is still working on it. > SMR drives have to read a whole band of shingled tracks, modify the small > region where the data has changed and then write the whole band of tracks > back > on the disk in one go. The onboard cache on drive managed SMRs (DM-SMR) is > meant to hide this from the OS by queuing up writes before writing them on > the > disk in a sequential stream, but if you keep hammering it with many random > writes you will soon exhaust the onboard cache and performance then becomes > glacial. > > Host managed SMRs (HM-SMR) require the OS and FS to be aware of the need for > sequential writes and manage submitted data sympathetically to this > limitation > of the SMR drive, by queuing up random writes in batches and submitting these > as a sequential stream. > > I understand the ext4-lazy option and some patches on btrfs have improved > performance of these filesystems on SMR drivers, but perhaps f2fs will > perform > better? :-/ > And that is exactly how it works. It is fast at first, what I see anyway, but once that buffer/cache fills up, leap year. It slows by half or more usually. The more that gets sent its way, the worse it gets it seems, watching progress from rsync. >> Another thing, I may switch to RAID one >> of these days. If I do, that drive isn't a good option. > Ugh! RAID striping will combine shingled bands across drives. A random > write > on one drive will cause other drives to read-modify-write bands. Whatever > speed benefit is meant to be derived from striping will be reversed. On a > NAS > application, where many users could be accessing the storage simultaneously > trying to save their interwebs downloads, etc., the SMR performance will nose > dive. > I marked the drive itself with a marker that it is a SMR drive. I'd never put that thing in a RAID setup or anything like RAID for that matter. I really don't want it in a LVM setup either. It will always run as a single drive and for nothing that I need to handle heavy writes most of the time. >> When I update my backups, I start the one I do with my NAS setup first. >> Then I start the home directory backup with the SMR drive. I then >> backup everything else I backup on other drives. I do that so that I >> can leave the SMR drive at least powered on while it does it's bumpy >> thing and I do other backups. Quite often, the SMR drive is the last >> one I put back in the safe. That bumpy thing can take quite a while at >> times. > Instead of using the SMR for your /home fs backup, you would do better if you > repurposed it for media files and document backups which do not change as > frequently. Well, usually my home backup has only small changes. Most of it is config files or my emails. I do add new videos on occasion but they stream pretty well to new spots. What made it hard that time tho, I moved a lot of files around and renamed things, same as moving to the file system I guess. That slowed things down a lot. I only use it because I only do backups once a week and it is a nice sized drive with plenty of room for home. Otherwise, I'd buy a better drive. If I had known it was a SMR drive before I bought it, I would have bought something else even if it cost a little more. That is one thing I like about the company I buy from, they sell mostly drives that are used in server type systems. When I asked, they said they don't stock any SMR drives. They can special order them for a big customer but they don't stock them. Plus, they have good deals and stand behind what they sell too. ;-) Now to figure out what I'm going to get into today. Dale :-) :-)
