On Sat, Nov 14, 2020 at 05:59:37PM +0100, Otto Moerbeek wrote:
> On Sat, Nov 14, 2020 at 04:59:22PM +0100, Mischa wrote:
>
> > On 14 Nov at 15:54, Otto Moerbeek <o...@drijf.net> wrote:
> > > On Sat, Nov 14, 2020 at 03:13:57PM +0100, Leo Unglaub wrote:
> > >
> > > > Hey,
> > > > my largest filesystem with OpenBSD on it is 12TB and for the minimal
> > > > usecase
> > > > i have it works fine. I did not loose any data or so. I have it mounted
> > > > with
> > > > the following flags:
> > > >
> > > > > local, noatime, nodev, noexec, nosuid, softdep
> > > >
> > > > The only thing i should mention is that one time the server crashed and
> > > > i
> > > > had to do a fsck during the next boot. It took around 10 hours for the
> > > > 12TB.
> > > > This might be something to keep in mind if you want to use this on a
> > > > server.
> > > > But if my memory serves me well otto did some changes to fsck on ffs2,
> > > > so
> > > > maybe thats a lot faster now.
> > > >
> > > > I hope this helps you a little bit!
> > > > Greetings from Vienna
> > > > Leo
> > > >
> > > > Am 14.11.2020 um 13:50 schrieb Mischa:
> > > > > I am currently in the process of building a large filesystem with
> > > > > 12 x 6TB 3.5" SAS in raid6, effectively ~55TB of storage, to serve as
> > > > > a
> > > > > central, mostly download, platform with around 100 concurrent
> > > > > connections.
> > > > >
> > > > > The current system is running FreeBSD with ZFS and I would like to
> > > > > see if it's possible on OpenBSD, as it's one of the last two systems
> > > > > on FreeBSD left.:)
> > > > >
> > > > > Has anybody build a large filesystem using FFS2? Is it a good idea?
> > > > > How does it perform? What are good tests to run?
> > > > >
> > > > > Your help and suggestions are really appriciated!
> > > >
> > >
> > > It doesn't always has to be that bad, on current:
> > >
> > > [otto@lou:22]$ dmesg | grep sd[123]
> > > sd1 at scsibus1 targ 2 lun 0: <ATA, ST16000NE000-2RW, EN02>
> > > naa.5000c500c3ef0896
> > > sd1: 15259648MB, 512 bytes/sector, 31251759104 sectors
> > > sd2 at scsibus1 targ 3 lun 0: <ATA, ST16000NE000-2RW, EN02>
> > > naa.5000c500c40e8569
> > > sd2: 15259648MB, 512 bytes/sector, 31251759104 sectors
> > > sd3 at scsibus3 targ 1 lun 0: <OPENBSD, SR RAID 0, 006>
> > > sd3: 30519295MB, 512 bytes/sector, 62503516672 sectors
> > >
> > > [otto@lou:20]$ df -h /mnt
> > > Filesystem Size Used Avail Capacity Mounted on
> > > /dev/sd3a 28.9T 5.1G 27.4T 0% /mnt
> > >
> > > [otto@lou:20]$ time doas fsck -f /dev/rsd3a
> > > ** /dev/rsd3a
> > > ** File system is already clean
> > > ** Last Mounted on /mnt
> > > ** Phase 1 - Check Blocks and Sizes
> > > ** Phase 2 - Check Pathnames
> > > ** Phase 3 - Check Connectivity
> > > ** Phase 4 - Check Reference Counts
> > > ** Phase 5 - Check Cyl groups
> > > 176037 files, 666345 used, 3875083616 free (120 frags, 484385437
> > > blocks, 0.0% fragmentation)
> > > 1m47.80s real 0m14.09s user 0m06.36s system
> > >
> > > But note that fsck for FFS2 will get slower once more inodes are in
> > > use or have been in use.
> > >
> > > Also, creating the fs with both blockszie and fragment size of 64k
> > > will make fsck faster (due to less inodes), but that should only be
> > > done if the files you are going to store ar relatively big (generally
> > > much bigger than 64k).
> >
> > Good to know. This will be mostly large files indeed.
> > That would be "newfs -i 64"?
>
> Nope, newfs -b 65536 -f 65536
To clarify: the default block size for large filesystems is already
2^16, but this value is taken from the label, so if another fs was on
that partition before, it might have changed. The default fragsize is
blocksize/8. When not specified on the command line, it is also taken
from the label.
Inode density is derived from the number of frgaments (normally 1
inoder per 4 fragments), if you increase framgent size, the number of
fragments drops and so the number if inodes.
A fragment is the minimal alloctation unit. So if you have lots of
small files you will waste a lot of space and potentially run out of
inodes. You only want to increase fragment size of you mostly store
large files.
-Otto
