A whole week! ZFS read/write pattern

Using dtrace, here is another SAN disk (of 4) of our zpool including the mail spool from a Cyrus IMAP server. I did a zoom on the first 2 TB of storage, where ZFS is very busy. The rest of 2 TB per storage disk is nearly not used. Here a whole week was monitored and converted to a movie. 5 minutes long green blinkenlights and red writing snakes. Enjoy!

Category:

Science & Technology

Tags:

• zfs
• zpool
• solaris
• dtrace
• cyrus
• imap

[bobjandal]

what is that kind of scattered leader to all the writes ? is it prepping the disk ahead of the upcoming write or something ?

[pascalgienger]

@bobjandal

It is scattered because the sequential writes skip used blocks. The "black holes" in the write worms are just blocks which are already taken (and valid).

[OClockedManITA]

woooooow

[bobjandal]

@pascalgienger ah cool - cheers :) man this sure is an awesome video - been playing it on repeat for ages...

but is it just me, or does it always look like there's two write worms ? the first dotty one, skipping the used blocks, then a solid one shortly after that just obliterates everything.

is this to do with your specific data pattern, not zfs design ?

copy on write seems like such a grand idea...

[richard3667]

this is really cool

[zalez71]

Awesome video, Pascal!