All my servers have an 8 GB empty file on disk • Hacker News Board

Re: All my servers have an 8 GB empty file on disk

#11

Post by AlisdairO » Thu, Mar 25, 2021, 7:07 PM UTC

One other option is increasing the reserved block count ( https://ma.ttias.be/change-reserved-blocks-ext3-ext4-filesys... ). This has the nice side effect of increasing the space available for critical daemons.

If you haven't customised this, in a pinch you can still lower it down a bit to buy some time.

Re: All my servers have an 8 GB empty file on disk

#12

Post by JshWright » Thu, Mar 25, 2021, 7:07 PM UTC

00deadbeef wrote: post #7

Isn’t using LVM and holding some space back a better solution for this? Also I keep databases on their own partition so that nothing else can accidentally fill up the space and lead to data loss.

rm /path/to/big.file is faster than looking up the commands to expand the LVM volume and grow the filesystem.

Re: All my servers have an 8 GB empty file on disk

#13

Post by tomaszs » Thu, Mar 25, 2021, 7:07 PM UTC

Interesting. I would try to notify myself when space is getting low. But I like the solution because of it's simplicity

Re: All my servers have an 8 GB empty file on disk

#14

Post by loloquwowndueo » Thu, Mar 25, 2021, 7:07 PM UTC

If you don’t have monitoring to tell you when the disk is more than X% full, then you’re at risk for more failure scenarios than just a full disk (usually trivial to buy time by deleting old logs).

Re: All my servers have an 8 GB empty file on disk

#15

Post by badcc » Thu, Mar 25, 2021, 7:07 PM UTC

This trick has certainly saved me more times than I am willing to admit! I usually roll with: `fallocate -l 8G DELETE_IF_OUT_OF_SPACE.img`

Re: All my servers have an 8 GB empty file on disk

#16

Post by jstanley » Thu, Mar 25, 2021, 7:08 PM UTC

Denvercoder9 wrote: post #9

> Copy commands and even deletions can fail or take forever as memory tries to swap to a full disk That's only a problem if your memory is full as well, and even then, I've never encountered a server that uses a swapfile instead of a swap partition.

That's also only a problem if your swap partition is mounted from a file on your filesystem, which is an exceedingly uncommon configuration.

Re: All my servers have an 8 GB empty file on disk

#17

Post by 00deadbeef » Thu, Mar 25, 2021, 7:08 PM UTC

JshWright wrote: post #12

00deadbeef wrote: post #7

Isn’t using LVM and holding some space back a better solution for this? Also I keep databases on their own partition so that nothing else can accidentally fill up the space and lead to data loss.

rm /path/to/big.file is faster than looking up the commands to expand the LVM volume and grow the filesystem.

They’re not hard to memorise. I never look them up.

Re: All my servers have an 8 GB empty file on disk

#18

Post by yjftsjthsd-h » Thu, Mar 25, 2021, 7:10 PM UTC

Denvercoder9 wrote: post #9

> Copy commands and even deletions can fail or take forever as memory tries to swap to a full disk That's only a problem if your memory is full as well, and even then, I've never encountered a server that uses a swapfile instead of a swap partition.

Even a swap file shouldn't matter, since it's still not sparse. The one exception is if you're on a system that dynamically adds and removes swap files - I believe darwin does that, and I think it might be possible to do on Linux(?) but I've not actually seen it done.

Re: All my servers have an 8 GB empty file on disk

#19

Post by Something1234 » Thu, Mar 25, 2021, 7:10 PM UTC

I have an empty leader on my hard drive so that I can recover if I accidentally nuke the front of it with dd while making a live usb. So it's not a bad idea, and it's super effective so far it hasn't been tested, and hopefully I never will need to.

Re: All my servers have an 8 GB empty file on disk

#20

Post by tyingq » Thu, Mar 25, 2021, 7:11 PM UTC

Careful how you create it. Several ways to create large files can make a sparse file, which I don't think removing will actually help later.