Average writes to Disk

stephenw10

What are you using to check the drive writes? What's the actual data it's giving you?

fireodo

@stephenw10 said in Average writes to Disk:

What are you using to check the drive writes? What's the actual data it's giving you?

On the one hand the smart value of LBA_written and on the other hand iostat -d 5 6.

stephenw10

And what values are you actually seeing there?

fireodo

@stephenw10 said in Average writes to Disk:

And what values are you actually seeing there?

iostat -d 5 6
             md0             ada0            pass0
  KB/t tps  MB/s   KB/t tps  MB/s   KB/t tps  MB/s
  0.00   0  0.00  15.55  14  0.21   0.38   0  0.00
  0.00   0  0.00  12.80  22  0.27   0.00   0  0.00
  0.00   0  0.00  14.67  15  0.21   0.00   0  0.00
  0.00   0  0.00  12.59  14  0.17   0.00   0  0.00
  0.00   0  0.00  14.67  14  0.20   0.00   0  0.00
  0.00   0  0.00  13.56  14  0.19   0.00   0  0.00

Using mathematics it comes to about 20GB/day

PS. On the LAB machine (the fresh 2.5.2 install) there are no other packages running. Basic pfsense.

SteveITS

@stephenw10 said in Average writes to Disk:

There was a bug at one time that was not mounting root as noatime

I looked, as we have some older routers, and found a few.

/dev/gptid/4eca01a4-9c0d-11e7-bbd9-0008a20cdf70 / ufs rw 1 1
devfs /dev devfs rw 0 0
/dev/md0 /var/run ufs rw 2 2
devfs /var/dhcpd/dev devfs rw 0 0

Just change rw to rw,noatime in /etc/fstab, and reboot?

fireodo

@steveits said in Average writes to Disk:

Just change rw to rw,noatime in /etc/fstab, and reboot?

In /etc/fstab there is only that:

"# Device Mountpoint FStype Options Dump Pass#
/dev/ada0p2 none swap sw 0 0"

And if you look in the beginning of the thread there is the output of mount -p - most every FS is mounted noatime.

stephenw10

Yup, exactly, just edit the fstab if you have some that were created at that time.

ZFS does write to the drive more than UFS by design. I'm not sure what might be done there.

Enabling RAM disks reduces it significantly but you wouldn't want to do that with Snort and pfBlocker running.

Steve

stephenw10

@fireodo said in Average writes to Disk:

In /etc/fstab there is only that:

Because you're running ZFS which doesn't use the fstab.

fireodo

@stephenw10 said in Average writes to Disk:

Enabling RAM disks reduces it significantly but you wouldn't want to do that with Snort and pfBlocker running.

That was my idea too but as you say - no way with snort&pfblockerNG ...

fireodo

@stephenw10 said in Average writes to Disk:

ZFS does write to the drive more than UFS by design.

Do you think that could be from ZFS? Because I have stopped most every service that can be stopped but the writings go on ...

On the other hand - is my installation so particular?

johnpoz

@fireodo what ssd are you using? Modern SSD even with 20GB a day you should still be like a 10 year lifespan..

I just looked up a shit $20 128GB ssd from lexar the ns100, and it lists 60TB write life.. at 20GB a day your still looking at 8 some years..

Off the cuff 20GB a day does seem like a lot... But even at that you should get decent life out of the SSD..

fireodo

@johnpoz said in Average writes to Disk:

what ssd are you using?

See my signature :-)

I already ordered some spare for ... just in case ;-)

johnpoz

@fireodo I don't see anything listed for 16GB size.. But the 64 is listed as

36.5TBW (64GB)

So you have to assume lower than that.. So yeah, prob not the best drives for lots of writes..

Lets call it half that.. Your looking at like 2.5 years only..

fireodo

@johnpoz said in Average writes to Disk:

@fireodo I don't see anything listed for 16GB size.. But the 64 is listed as

36.5TBW (64GB)

So you have to assume lower than that.. So yeah, prob not the best drives for lots of writes..

Lets call it half that.. Your looking at like 2.5 years only..

Of course this all sounds reasonable but for me its strange that a older APU (that I have as quick replacement in case of hardware failure - i do much HomeOffice) with 2.4.5 shows insignificant writes to disk (also ZFS) far far away from 20GB/day.

AndyRH

Extra space will get longer life, more room for TRIM to work with and at todays prices it is worth the investment IMHO.

fireodo

@andyrh said in Average writes to Disk:

Extra space will get longer life, more room for TRIM to work with and at todays prices it is worth the investment IMHO.

I understand that all very well - its the Researcher in me that wants to find out what the real cause of all that is! Eliminating the symptoms dont eliminate the ill (if it is one) ;-)

AndyRH

@fireodo said in Average writes to Disk:

its the Researcher in me that wants to find out what the real cause of all that is!

Agreed.
Not everyone does that. I like to know how it works too.

fireodo

@johnpoz Is this process telling you (or somebody else) something?

zpool-zroot{txg_thread_enter}

This process is doing very much writing when I use
top -SH -o write (and after that "m")

johnpoz

I see that pop up every few seconds on mine as well

But I have no idea what it is or does to be honest..

Maybe a zfs guru will chime in - that sure isn't me ;)

fireodo

@johnpoz said in Average writes to Disk:

But I have no idea what it is or does to be honest..

I googled about it but I did not find anything concludent - that's why I was asking.

Would you show me your output of iostat -d 5 6 ?