Flash/SSD MySQL and performance

It seems that MySQL and SSD performance is popular. I just saw Kazuho at Work: Benchmarking SSD for MySQL and last night I listened to Blog Talk Radio: Innovation Insider - Flash Memory Technology with Michael Cornwell. The latter discusses more than flash performance with references to MySQL benchmarking. It also covers price/performance, reliabilty and the economics of power consumption and heat dissipation for SSD vs spinning storage.

The ZFS Device Shuffle

I shot this video/screencast demo thing nine or ten months ago. The audio from the datacenter was terrible. I have been sitting on it and some voice overs that I wasn't pleased with for about 4 months. Today I decided that it was time finally get it published, did another voice over and while it isn't perfect its good enough.

This video was inspired by CSI: Munich I watched it and thought, wait I have an x4500!

Link to ZFS Device Shuffle on Mediacast

Here instead we will try an object embedded quicktime found at Bye Bye Embed, the video above is being served from the all new and improved http://mediacast.sun.com

 

Edit: I have uploaded an amplified version, it appears that unless you are using good isolation earbuds or have relatively good quality speakers you can't really hear the audio portion. The trial copy of "Sound Studio" I downloaded did a wonderful job of letting me amplify the audio. The audio and video are the same, only the link has changed (It does not appear possible to replace the original content )

While I was at it we just released a new version of mediacast.sun.com (I could never get my login to the old one working). For some reason smugmug is taking 23MB of video and reprocessing it to 94MB. I can download that in about 3 minutes but the size is ridiculous. (No wonder my wife said it took forever to play)

 

(This is the smugmug video, I still like the interface it just isn't quite doing it for me otherwise)

 Edit: A bit of clarity I should go to bed at 02:30 instead of messing with my blog

Cat Proof External Storage

What happens when you disconnect the drive on the fly?
(e.g. set up a tripping hazard for your cat)

You get this message

What happens when you do the same thing to a ZFS pool? This is no different
than what you get on Solaris, except it is on my Mac Book Pro.

  pool: p1
   state: DEGRADED
  status: One or more devices could not be opened.  Sufficient replicas exist for
      the pool to continue functioning in a degraded state.
  action: Attach the missing device and online it using 'zpool online'.
     see: http://www.sun.com/msg/ZFS-8000-D3
   scrub: scrub completed with 0 errors on Sat Dec  8 01:44:00 2007
  config:
 
      NAME         STATE     READ WRITE CKSUM
      p1           DEGRADED     0     0     0
        mirror     DEGRADED     0     0     0
          disk7s1  UNAVAIL      0   114     0  cannot open
          disk0s3  ONLINE       0     0     0

Fortunately for me, my system keeps merrily chugging along.

Unfortunately (sort of) and this is much more of an issue on my Mac than on
any other system I am adding and removing devices much more frequently.

When I last connected the external disk and imported the pool I had 6
more "disks" visible to the system (really a usb thumb drive) another FW
device and a few SW RAID devices. This caused my nice portable external
FW disk to appear as disk7.

  diskutil list             
  /dev/disk0
     #:                       TYPE NAME                    SIZE       IDENTIFIER
     0:      GUID_partition_scheme                        *149.1 Gi   disk0
     1:                        EFI                         200.0 Mi   disk0s1
     2:                  Apple_HFS noroute                 88.9 Gi    disk0s2
     3:                  Apple_HFS                         57.0 Gi    disk0s3
     4:                  Apple_HFS noroute_2_1_2           2.6 Gi     disk0s4
  /dev/disk1
     #:                       TYPE NAME                    SIZE       IDENTIFIER
     0:     FDisk_partition_scheme                        *55.9 Gi    disk1
     1:                  Apple_HFS                         55.9 Gi    disk1s1 

 

The difference between the zpool status and diskutil list output
is the device configured for the pool is disk7s1 not the currently visible
disk1s1.

I don't know how to recover from this situation live. If the device has not
renumbered you just zpool online p1 disk7s1 to reconnect on a different
device number I export and import the pool again.

To state that another way, I don't know how to effectively do:
zpool online p1
similar to
zpool replace p1
(the replace, even with -f, failed telling me that was busy)

I have just requested a pre-release tarball that is reported to fix some bugs
in the current beta. We will see how it goes.

Other Observations:

Once you load the RW kext, it appears that anyone can do anything to the ZFS pools
and filesystems. On my single user system this is OK. I am the only user and guest
accounts are disabled. e.g. Initiate a scrub as a non-admin guest account or create a
snpashot as nobody (sudo -u nobody zfs snapshot p1/Music@nobody)

You CANNOT download music from the iTunes store in the current beta. you get a
permission error. I can however add music from local files.

 

Edit: Cleaned up the block quotes a bit, still not really rendering as one might hope.