On 5/4/20 7:28 PM, nick wrote:
On 2020-05-04 2:12 p.m., Alvin Starr via talk wrote:
On 5/4/20 1:26 PM, Lennart Sorensen via talk wrote:
On Mon, May 04, 2020 at 04:38:28PM +0200, ac via talk wrote:
Hi Alvin,
On a 2TB dataset, with +-600k files, I have piped tree to less with
limited joy, it took a few hours and at least I could search for
what I was looking for... - 15TB and 100M is another animal though
and as disk i/o will be your bottleneck, anything will take long, no?
now, for my own info/interest, can you tell me which fs is used for this
ext3?
Hmm, sounds awful slow.
Just for fun I ran find on one of my drives:
# time find /data | wc -l
1825463
real 3m57s.208s
That is with 5.3T used out of 6.0TB.
Running it a second time when it is cached takes 7.7s. Tree takes 14.7s.
Another volume:
# time find /mythdata | wc -l
54972
real 0m1.924s
That is with 15 TB out of 15 TB in use (yes that one always fills up
for some reason).
Both of those are lvm volumes with ext4 on top of software raid6 using
5400rpm WD red drives.
Seems either XFS is unbelievable bad, or there isn't enough ram to cache
the filesystem metadata if you are having a problem with 100M files.
I only have a measly 32GB in my home machine.
I believe the directory hierarchy has a lot to do with the performance.
It seems that the listing time is non-linear although I do not believe its an
N^^2 kind of problem.
I would have said the same as you before I started having to deal with 10's of
millions of files.
The first question I would have is how big are the actual files versus space
used. Most file systems
try to merge files that don't allocate in a single block to save blocks and get
better space usage.
Assuming a) the size of the files being rather small and b) The amount, I would
be curious if ReiserFS
or brtfs helps either as most have much better tail merging into metadata
blocks to my knowledge. Better
packing the small files can help as disk seeks are a problem here it seems. My
disks will solve to like
10 MB/S on ext4 with lots of small files like this due to seeks.
The files are generally a few hundred KB each. They may run into a few
MB but that's about it.
I use to use ReiserFS back in the days of ext2/3 but it kind of fell out
of favor after the lead developer got sent away for murder.
Reiser was much faster and more reliable than ext at the time.
It would actually be interesting to see if running a reiserfs or btrfs
filesystem would actually make a significant difference but in the long
run I am kind of stuck with Centos/RH supported file systems and reiser
and btrfs are not part of that mix anymore.
I am not sure how much I can get by tweaking the filesystem.
I would need to get a 50x -100x improvement to make backups complete in
a few hours.
Most stuff I have read comparing various filesystems and performance are
talking about percentage differences that is much less than 100%.
I have a feeling that the only answer will be something like Veeam where
only changed blocks are backed up.
A directory tree walk just takes too long.
The other question as pointed out here is how much memory the page cache and
other kernel caches are
using. I would check /proc/meminfo to start as this may be another logical
solution already pointed
out.
Maybe that helps,
Nick
--
Alvin Starr || land: (647)478-6285
Netvel Inc. || Cell: (416)806-0133
al...@netvel.net ||
---
Post to this mailing list talk@gtalug.org
Unsubscribe from this mailing list https://gtalug.org/mailman/listinfo/talk
