iTunes on a zfs store == laggy playback ?

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iTunes on a zfs store == laggy playback ?

Post by dene » Thu Nov 08, 2012 3:22 pm

Have a mid-2011 Mac mini server (2.0GHz i7, 16GB ram, dual 750GB internal SATA) and having my iTunes library (25257 items, 155.85GB) sitting on the zfs store means there's a 1-2 second delay every time I skip a song

ZFS looks like this:

pool: stor
state: ONLINE
scan: scrub repaired 0 in 2h5m with 0 errors on Thu Nov 8 18:44:02 2012
config:

NAME STATE READ WRITE CKSUM
stor ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
GPTE_0B605F65-528A-40B0-B6A5-6B8FFD9909BA ONLINE 0 0 0 at disk1s2
GPTE_26853D51-4950-4DB6-A26B-2C4FCFEE401E ONLINE 0 0 0 at disk2s2

errors: No known data errors


If i put the same library on an HFS+ disk via firewire800 I get no such lag when switching tracks.

Thoughts/ideas/diagnostics to run?
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Re: iTunes on a zfs store == laggy playback ?

Post by si-ghan-bi » Thu Nov 08, 2012 4:35 pm

iMac 2.4 GHz mid-2007, 6 GB RAM, 2x 3TB mirror ZFS FW800, iTunes library and music on external drive. No issues.
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Re: iTunes on a zfs store == laggy playback ?

Post by churnd » Thu Nov 08, 2012 10:48 pm

I've noticed a few glitches, specifically with my local movie catalog. Selecting one video to another has a slight noticeable delay. If I move the iTunes Library back to an HFS+ volume, it's fine. I think there are some Finder specific metadata type things that iTunes uses that may either not be working with ZFS or may be sluggish. No idea where to begin testing/debugging. However, I'm also using a mirror like the OP. I noticed the second poster isn't. Maybe that's part of it.
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analysis

Post by grahamperrin » Fri Nov 09, 2012 1:04 am

dene wrote:… laggy … dual 750GB internal SATA … 


Code: Select all
   mirror-0                                     ONLINE       0     0     0
     GPTE_0B605F65-528A-40B0-B6A5-6B8FFD9909BA  ONLINE       0     0     0  at disk1s2
     GPTE_26853D51-4950-4DB6-A26B-2C4FCFEE401E  ONLINE       0     0     0  at disk2s2


As both are used for ZFS, I assume that part of one is used for the JHFS+ startup volume for OS X.

Please see:

latency: avoid mixing HFS Plus and ZFS on a single hard disk
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Re: analysis

Post by dene » Fri Nov 09, 2012 8:42 pm

As both are used for ZFS, I assume that part of one is used for the JHFS+ startup volume for OS X.

Please see:

latency: avoid mixing HFS Plus and ZFS on a single hard disk



Boot drive is currently sitting on a SSD via thunderbolt, so both internal disks are fully dedicated to ZFS.
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link and thoughts

Post by grahamperrin » Sat Nov 10, 2012 12:05 am

dene wrote:… If i put the same library on an HFS+ disk via firewire800 I get no such lag when switching tracks.


Maybe of interest, although I doubt that it will explain your case:

Performance issue with FW800 connection order?

Are any other devices on Thunderbolt, alongside your SSD startup volume?

If so, what's the order of devices?

dene wrote:Thoughts/ideas/diagnostics to run?


sysdiagnose and/or zstat
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Re: iTunes on a zfs store == laggy playback ?

Post by witchbutter » Mon Nov 12, 2012 1:59 am

I'm having the same issue now that I upgrade from MacZFS to Zevo ZFS and recreated my zpool using ZFS 28.

In Mac ZFS with ZFS 8 I never had any issues like this although I had another bizarre issue where folders named using special characters like ö would cause the folder to blink in and out of existence and I'm glad that's fixed.

I get a spinning beachball every time I edit any song metadata or click to a song in the library.
The following lines were appearing each time in the console:
Code: Select all
11/11/12 11:47:15.767 PM iTunes[252]: Possible unresolved transaction race -102/(iTunesMedia/Music/Compilations/Love Language EP [CLS201206],(null))


Also initially I had to grant my user account and the administrators group rights to access my ZFS volume. In addition this line appeared over and over in the console:
Code: Select all
11/11/12 11:31:46.098 PM com.apple.kextd[12]: Can't create kext cache under / - owner not root.

Corrected by:
Code: Select all
sudo chown root:admin /


A permissions repair shows no issues.
Does iTunes have some HFS+ only bs going on here? I despise iTunes software, I think it's absolute garbage, only I have an iPhone so I have to use it. If the only solution is to go back to HFS+ I'm going to have to find an alternative.
Any ideas?

**edit**
My setup is all internal WD RE4 drives in raidz1 on Z77X so I don't think your slowness issue has to do with the interface necessarily.
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cross references

Post by grahamperrin » Mon Nov 12, 2012 7:07 pm

witchbutter wrote:… characters like … would cause the … to blink in and out of existence …


For explanations, please see NFD: normalization=formD (normalisation form D)

… initially I had to grant my user account and the administrators group rights to access my ZFS volume.


The need to change ownership is noted under Permission probleme & question

… over and over in the console:
Code: Select all
11/11/12 11:31:46.098 PM com.apple.kextd[12]: Can't create kext cache under / - owner not root.

… 


New topic: Can't create kext cache under / - owner not root
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Re: iTunes on a zfs store == laggy playback ?

Post by grahamperrin » Mon Nov 12, 2012 7:37 pm

witchbutter wrote:… spinning beachball every time I edit any song metadata or click to a song in the library.
The following lines were appearing each time in the console:
Code: Select all
11/11/12 11:47:15.767 PM iTunes[252]: Possible unresolved transaction race -102/(iTunesMedia/Music/Compilations/Love Language EP [CLS201206],(null))


http://duckduckgo.com/?q=%22Possible+un ... %22+iTunes finds a few items, I might take a look later …

Does iTunes have some HFS+ only bs going on here?


I don't think so. Here with OS X 10.8.2 on a MacBookPro5,2 with 8 GB memory I don't have a problem with iTunes using ZEVO ZFS for storage. (It's not super-fast, but it's no slower than it was with JHFS+.)

Which OS do you use? Which version of ZEVO?

How much memory, etc.?

Please paste outputs from five commands:

Code: Select all
diskutil list
diskutil coreStorage list
zpool list
zfs list
zpool status


(For the pastes, in phpBB, five separate blocks may be easier to read.)

Thanks
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Re: iTunes on a zfs store == laggy playback ?

Post by witchbutter » Wed Nov 14, 2012 2:37 am

16GB ram. 10.8.2. Zevo 1.1.1.

diskutil list
Code: Select all
nightside:~ witchbutter$ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *256.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS Nightside               255.7 GB   disk0s2
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *128.0 GB   disk1
   1:                        EFI                         104.9 MB   disk1s1
   2:         Microsoft Reserved                         134.2 MB   disk1s2
   3:       Microsoft Basic Data                         127.8 GB   disk1s3
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.5 TB     disk2
   1:                        EFI                         209.7 MB   disk2s1
   2:                        ZFS                         1.5 TB     disk2s2
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.5 TB     disk3
   1:                        EFI                         209.7 MB   disk3s1
   2:                        ZFS                         1.5 TB     disk3s2
/dev/disk4
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.5 TB     disk4
   1:                        EFI                         209.7 MB   disk4s1
   2:                        ZFS                         1.5 TB     disk4s2
/dev/disk5
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:             zfs_pool_proxy RE4                    *4.5 TB     disk5


diskutil coreStorage list
Code: Select all
nightside:~ witchbutter$ diskutil coreStorage list
No CoreStorage logical volume groups found


zpool list
Code: Select all
nightside:~ witchbutter$ zpool list
NAME    SIZE   ALLOC    FREE     CAP  HEALTH  ALTROOT
RE4   4.09Ti   278Gi  3.82Ti      6%  ONLINE  -


zfs list
Code: Select all
nightside:~ witchbutter$ zfs list
NAME    USED   AVAIL   REFER  MOUNTPOINT
RE4    185Gi  2.50Ti   185Gi  /Volumes/RE4


zpool status
Code: Select all
nightside:~ witchbutter$ zpool status
  pool: RE4
 state: ONLINE
 scan: none requested
config:

   NAME                                           STATE     READ WRITE CKSUM
   RE4                                            ONLINE       0     0     0
     raidz1-0                                     ONLINE       0     0     0
       GPTE_D059E27B-EF5A-40CA-BB8A-1E1137884BEC  ONLINE       0     0     0  at disk2s2
       GPTE_F41FF023-3F94-4649-BD59-37723ABC41A2  ONLINE       0     0     0  at disk3s2
       GPTE_00536E17-2215-4AED-A297-7B6B6CA97362  ONLINE       0     0     0  at disk4s2

errors: No known data errors
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