Jakob Borg, You basically gave me exactly what I wanted. Thank you!!!
The focus of my question was actually getting these values for SSDs specifically. Those SMART statistics are exactly what I was looking for. I'll test this on my own SSDs as soon as possible. When I get around to it, I'd like to create an Ohai plugin so these values can be reported back to Chef Server. Marsell Kukuljevic - I'm completely with you on MTBF being a poor measure for spinning disks. On the other hand, I think that for SSDs with predictable write failure, MTBF is a valuable concept. Keith Wesolowski - Thanks for the iostat and kstat pointers. If for any reason the SMART statistics aren't good enough for me, I'll definitley be using those tools. Actually your reply caused me to find some interesting search results online, so thanks again. On Mon, Apr 7, 2014 at 1:20 PM, Jakob Borg <[email protected]> wrote: > 2014-04-07 18:13 GMT+02:00 Evan Rowley <[email protected]>: > > > > > I'd like to measure the total amount of data written over time to the > physical devices that make up zpool zils, l2arcs, and vdevs. Each one of > these physical devices has a projected Mean Time Before Failure (MTBF), > often measured in writes or data written to the device, which I'd like to > compare with the total number of writes to the device. > > > > The "zpool iostat" command can do this for a given period of time, but > unless I'm mistaken, it can't do this continually for an unpredictable > amount of time. > > > > I'm imagining that something like this can be done using dtrace, but I'm > not completley certain if that is the best way to tackle the problem. > > > > Are there any other ways to do this? (before i go re-inventing the wheel) > > Many SSD:s keep SMART-accessible counters for data read and written; > > [root@anto ~]# /opt/smartmontools/sbin/smartctl -d sat,12 -A > /dev/rdsk/c3t1d0p0 > ... > ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED > WHEN_FAILED RAW_VALUE > ... > 241 Host_Writes_32MiB 0x0032 100 100 000 Old_age Always > - 355603 > 242 Host_Reads_32MiB 0x0032 100 100 000 Old_age Always > - 64535 > > Haven't seen the same on any spinning disks... > > //jb > *smartos-discuss* | > Archives<https://www.listbox.com/member/archive/184463/=now> > <https://www.listbox.com/member/archive/rss/184463/24484565-d47e1b4e> | > Modify<https://www.listbox.com/member/?&;>Your Subscription > <http://www.listbox.com> > -- - EJR ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
