iTunes on a zfs store == laggy playback ?

This forum is to find answers to problems you may be having with ZEVO Community Edition.

Moderators: jhartley, MSR734, nola

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

Post by dbrady » Wed Nov 14, 2012 8:22 am

We have seen cases where certain filenames cause the lag. When iTunes can't resolve names it looks to an alternate DB for mappings (hence the lag).

If the lag is significant (like > 10 sec), then a spindump(8) using the pid of iTunes would help us isolate any zfs-side latency/stall.
dbrady Offline


 
Posts: 67
Joined: Wed Sep 12, 2012 12:43 am

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

Post by witchbutter » Sat Nov 17, 2012 11:54 am

The wheel is a few seconds but probably not 10. Here's a spindump of using command I to get to 'Get Info'. Is there somewhere I can learn how to read all this output?
Attachments
iTunes_252.spindump.txt.zip
spindump
(113.17 KiB) Downloaded 9 times
witchbutter Offline


 
Posts: 6
Joined: Mon Sep 17, 2012 1:31 am

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

Post by witchbutter » Sun Nov 18, 2012 8:57 pm

I decided to purchase Enqueue today. Enqueue has no issues playing back from my ZFS volume, which means to me this is a problem with the iTunes software rather than ZFS.
witchbutter Offline


 
Posts: 6
Joined: Mon Sep 17, 2012 1:31 am

spindump analysis

Post by grahamperrin » Mon Nov 19, 2012 1:17 pm

witchbutter wrote:…Is there somewhere I can learn how to read all this output?


In Stack Exchange:

Spindump analysis instructions?

I added a bounty, and a mention in Ask Different Chat.
grahamperrin Offline

User avatar
 
Posts: 1596
Joined: Fri Sep 14, 2012 10:21 pm
Location: Brighton and Hove, United Kingdom

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

Post by churnd » Wed Nov 21, 2012 12:23 pm

grahamperrin wrote:
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


Just wanted to contribute that I'm getting the same race error condition as the quoted author above:

Code: Select all
Nov 21 12:13:38 server.local iTunes[265]: Possible unresolved transaction race -104/(iTunes/iTunes Media/Movies/Limitless,(null))
Nov 21 12:13:46 --- last message repeated 2 times ---



My setup is just a mirror between two WD Black 1TB drives, not a raidz config as above. However, it does seem that this problem seems to affect redundant pools of some kind, whereas it won't affect single vdev pools


Just for reference, the output of the above commands on my system as well:

Code: Select all
$ diskutil list; diskutil coreStorage list; zpool list; zfs list; zpool status
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *240.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS Server                  239.2 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk1
   1:                        EFI                         209.7 MB   disk1s1
   2:                        ZFS                         999.9 GB   disk1s2
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk2
   1:                        EFI                         209.7 MB   disk2s1
   2:                        ZFS                         999.9 GB   disk2s2
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk3
   1:                        EFI                         209.7 MB   disk3s1
   2:                        ZFS                         499.8 GB   disk3s2
/dev/disk4
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk4
   1:                        EFI                         209.7 MB   disk4s1
   2:                        ZFS                         499.8 GB   disk4s2
/dev/disk5
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk5
   1:                        EFI                         209.7 MB   disk5s1
   2:                  Apple_HFS Backup                  999.9 GB   disk5s2
/dev/disk6
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:             zfs_pool_proxy Media                  *999.7 GB   disk6
/dev/disk7
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:             zfs_pool_proxy Docs                   *498.2 GB   disk7

No CoreStorage logical volume groups found

NAME     SIZE   ALLOC    FREE     CAP  HEALTH  ALTROOT
Docs    464Gi   196Gi   268Gi     42%  ONLINE  -
Media   931Gi   216Gi   715Gi     23%  ONLINE  -
NAME     USED   AVAIL   REFER  MOUNTPOINT
Docs    196Gi   261Gi   196Gi  /Volumes/Docs
Media   216Gi   700Gi   216Gi  /Volumes/Media


  pool: Docs
 state: ONLINE
 scan: scrub repaired 0 in 0h44m with 0 errors on Fri Oct 26 07:10:56 2012
config:

   NAME                                           STATE     READ WRITE CKSUM
   Docs                                           ONLINE       0     0     0
     mirror-0                                     ONLINE       0     0     0
       GPTE_93832868-0104-4FFE-BB43-CF091E72DE4A  ONLINE       0     0     0  at disk3s2
       GPTE_1F2E2CC8-B044-42E2-B2DB-24D8BD350153  ONLINE       0     0     0  at disk4s2

errors: No known data errors

  pool: Media
 state: ONLINE
 scan: scrub canceled on Sun Oct 21 22:52:15 2012
config:

   NAME                                           STATE     READ WRITE CKSUM
   Media                                          ONLINE       0     0     0
     mirror-0                                     ONLINE       0     0     0
       GPTE_6630A812-36D4-4527-8C13-CA532551B850  ONLINE       0     0     0  at disk1s2
       GPTE_CCC7D1BD-0FE8-44AC-8A75-EB9464B0C5B9  ONLINE       0     0     0  at disk2s2

errors: No known data errors
churnd Offline


 
Posts: 9
Joined: Sat Sep 15, 2012 8:28 am

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

Post by churnd » Mon Dec 03, 2012 6:26 am

I destroyed the mirror & re-created a single vdev pool & the problem seems to be gone, so I think it's safe to say it only affected redundant pools.
churnd Offline


 
Posts: 9
Joined: Sat Sep 15, 2012 8:28 am

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

Post by hendrst1 » Mon Dec 03, 2012 2:44 pm

I am running a 500 Gb iTunes library from a ZFS mirrored pair attached via eSata (Sans digital 5 disk Toweraid, Firmtek 4 port eSata card in '09 Mac Pro, 16 Gb ram). No lag whatsoever.
hendrst1 Offline


 
Posts: 14
Joined: Sun Nov 25, 2012 2:15 pm

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

Post by churnd » Sun Dec 23, 2012 11:00 am

What I'm noticing, I wouldn't call "lag", but rather inconsistent playback. It only seems to happen when playing a video over home sharing to an iPad. It doesn't happen all the time either, seems to be random. What will happen is the "Videos" app will be come unresponsive while streaming the video. The video will keep playing, but the controls of the video become unresponsive. I have to kill the "Videos" app & wait for the playback to cease on it's own, usually about 2 mins later. This does not seem to happen when playing via Apple TV.

I don't think it would be considered a bug with the Videos app b/c it didn't happen when my iTunes library was on an HFS+ volume. I'm thinking there's some HFS+ specific metadata that's missing, which is causing the problems with the streaming. Almost as if it has something to do with seeking the correct time in the video.

The only "race" errors I see in the logs now are when I try to play music, not videos as per when I had the drives mirrored.
churnd Offline


 
Posts: 9
Joined: Sat Sep 15, 2012 8:28 am

HFS Plus-specific metadata

Post by grahamperrin » Wed Dec 26, 2012 3:40 am

churnd wrote:… thinking there's some HFS+ specific metadata that's missing …


I doubt it …
grahamperrin Offline

User avatar
 
Posts: 1596
Joined: Fri Sep 14, 2012 10:21 pm
Location: Brighton and Hove, United Kingdom

Cross reference

Post by grahamperrin » Sat May 04, 2013 2:32 pm

churnd wrote:… I'm getting the same race error condition as the quoted author above:

Code: Select all
Nov 21 12:13:38 server.local iTunes[265]: Possible unresolved transaction race -104/(iTunes/iTunes Media/Movies/Limitless,(null))
Nov 21 12:13:46 --- last message repeated 2 times ---

… 


Cross reference: iTunes locking up (2013-05-03)
grahamperrin Offline

User avatar
 
Posts: 1596
Joined: Fri Sep 14, 2012 10:21 pm
Location: Brighton and Hove, United Kingdom

Previous

Return to Troubleshooting

Who is online

Users browsing this forum: bileyqrkq, ilovezfs and 0 guests

cron