171–180 of 231 posts
I'm still waiting for bcachefs upstreaming.
Wonder if this will make it into Synology DSM 7.2. Seems unlikely based on the timing.
Unlikely, I am on DSM 7.1 and it is 4.4.180+, although I know heavily patched. I have read DSM 7.2 will land 5.10.
But I do hope there will be model, especially entry model that comes with 5.10.
Synology's Linux timeline is simply too slow.
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The way I used to do it (back then getting grub/initrd raid aware wasn't really doable - not sure about now) with mdadm was to use RAID1 on the boot volume such that a disk from a broken mirror was still usable by itself. Other volumes were RAID 5 or 10 etc.
How would a mirrored boot work in practice? Normally the first bootable partition gets loaded if it’s corrupt, it would keep failing at the same bad sectors. Would it randomly pick one of the bootable disks? That way you have an n-1/n chance of avoiding the bad disk?
The same way it has worked for the past 30+ years: the firmware boots from first designated boot device; if that device isn't bootable, it moves on to the next one. The next one boots since it's part of a mirror and has all the necessary data to do so, and in the rare case where the device is "half bootable" one would simply intervene and select the next good bootable device manually.
But is the RAID handling remotely sane yet? See https://arstechnica.com/gadgets/2021/09/examining-btrfs-linu... It has gems such as: * It won't boot on a degraded array by default, requiring manual action to mount it * It won't complain if one of the disks is stale * It won't resilver automatically if a disk is re-added to the array I think the first is the killer. RAID is a High Availability measure. Your system is…
Regarding resilvering, I am amazed by ZFS' capability of quickly bringing a stale mirror back into synchronization. I have used the FUSE port of ZFS to write only one member of a mirroset, then upon mounting both members elsewhere, the stale mirror was very quickly resilvered, so ZFS was able to determine only the blocks needing to be refreshed. In btrfs, I understand that this requires a rebalance, which will read/w…
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Is there a zfs native way to create raid0 disks now? On Linux I usually set up a linear mapping with dmsetup, and then point zfs to that. But this hides the native disks from zfs. I've done that a couple times to make a bunch of mismatched disk fit into zfs's requirement that all are of the same size. The ability to work with a mix of disk sizes is one advantage of btrfs - if you remember to be extra careful on a dis…
> Is there a zfs native way to create raid0 disks now? zpool create swimming disk1 disk2 … That has worked for over 15 years.
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The list of bugs and counter-intuitive design decisions in BTRFS RAID should make anyone pause before ever considering it as a viable filesystem for anything . It's like people justifying MySQL saying that it's okay for it to lose or corrupt data, and that transactional integrity doesn't matter as much as people say it does. Yeah, maybe if you're website is a blog. But anyone storing real data should run away screami…
I've had more issues with my ZFS arrays than the BTRFS ones. The Linux implementation is pretty awful, with it demanding that it uses the absolute `/dev/sdx` reference even if you try to build it using serials or other unchaging reference. Replace a disk and then after the next restart it fails to bring up the RAID because `sdf` points to a different disk. At least BTRFS uses internal UUIDs so can bring up the arrays…
But is the RAID handling remotely sane yet? See https://arstechnica.com/gadgets/2021/09/examining-btrfs-linu... It has gems such as: * It won't boot on a degraded array by default, requiring manual action to mount it * It won't complain if one of the disks is stale * It won't resilver automatically if a disk is re-added to the array I think the first is the killer. RAID is a High Availability measure. Your system is…
Every discussion about btrfs immediately escalates to how the btrfs RAID support develops. But btrfs is useful on its own without that mode.
Should you wish to put a btrfs file system on software RAID (DM), you can still do that. The btrfs RAID modes are something else, where you cut the DM driver out of the picture. That's not going to be as well tested as plain old DM, even if it works, and it doesn't offer any functionality beyond plain DM RAID.
If the use case is storing real data, you want the data storage layer to be as well tested as possible. There's also more to software RAID than the block device. You want a mature resilvering daemon on a well tested schedule, and you need working monitoring to alert you of issues. RAID without monitoring will only delay the inevitable.
I'm still waiting for bcachefs upstreaming.
Yeah, looks like that one is actually designed to do what it does, not just "somehow implemented". The BTRFS bugs fixed in every kernel release for how many years now? are horrific and show that BTRFS is crawling with corner cases.
... just use FreeBSD with OpenZFS for RAIDZ/RAIDZ2/RAIDZ3 pools instead.
... or even OpenZFS on Linux.
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> That's the only purpose for it. That's not the only purpose for it. There's three reasons I can think of that you might set up a RAID array: * You want better uptime. (your use case) * You want to protect from data loss. (my assumption was that this is the most common use case, but I could be wrong. This also helps with uptime because there's nothing worse for uptime than having to restore lost data from a cold bac…
RAID 0 should be called AID, since it’s not really RAID.