On Sun, Nov 15, 2020 at 8:59 AM Mischa <obs...@high5.nl> wrote:
> On 15 Nov at 14:52, Otto Moerbeek <o...@drijf.net> wrote:
> > fsck wil get slower once you start filling it, but since your original
> > fs had about 104k files it expect it not getting too bad. If the speed
> > for your usecase is good as well I guess you should be fine.
>
> Will see how it behaves and try to document as much as possible.
> I can always install another BSD on it. ;)
>
To give a very rough idea, here is a sample running fsck on an FFS2
file system with a fairly large number of files:
$ df -ik /nfs/archive
Filesystem 1K-blocks Used Avail Capacity iused ifree %iused
Mounted on
/dev/sd1g 12308149120 7477490128 4215251536 64% 4800726 383546408
1% /nfs/archive
$ doas time fsck -f /nfs/archive
** /dev/sd1g (6d3438729df51b22.g) (NO WRITE)
** Last Mounted on /nfs/archive
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
** Phase 5 - Check Cyl groups
4800726 files, 934686266 used, 603832374 free (35534 frags, 75474605
blocks, 0.0% fragmentation)
3197.25 real 35.86 user 66.03 sys
This is on older hardware, and not running the most recent release.
The server is a Dell PowerEdge 2900 with a PERC H700 controller, and
4 WD Red Pro 8TB disks (WD8001FFWX-6) forming a RAID10 volume
containing 3 small 1TB file systems and 1 large 12TB file system. The
OS is OpenBSD 6.1/amd64. All the file systems on this volume are
mounted with the softdep option and the big one has noatime as well.
The time to run fsck is really only an issue when the server reboots
unexpectedly (i.e. due to a power outage). Coming up after a proper
reboot or shutdown is very fast due to the file systems being clean.
A UPS can help avoid most of these power-related reboots. Alas, this
particular server was connected to a UPS with a bad battery so it has
rebooted due to power outages at least a half-dozen times this year,
each of them involving a fairly long fsck delay. I finally took the time
last week to replace the UPS batteries so going forward this should
be much less of a problem. I do recommend the use of a UPS (and
timely replacement of batteries when needed) if you are going to
host very large FFS2 volumes.
I have never lost files due to a problem with FFS2 (or with FFS for that
matter), but that is no reason not to perform regular backups. For this
particular file system I only back it up twice a year, but the data on it
doesn't change often. File systems with more 'normal' patterns of usage
get backed up weekly. The practice of taking regular backups also helps
ensure that 'bit rot' is detected early enough that it can be corrected.
-ken
