[Samba] Sudden unexplained slowness on share (caused by duplicate UID?)

ash-samba at comtek.co.uk ash-samba at comtek.co.uk
Wed Aug 31 16:49:18 UTC 2016


Hi,

We have 5 Samba domain controllers, and 4 file servers. All are 
4.2.10-Debian. Our file servers have been working fine until recently 
(on the 26th), when suddenly access to the 
\\users.store.example.com\user share (hostname p-cats) became extremely 
slow.

Access to other shares on other machines is fine, and users is 128G 
total (smaller than other shares). The machine isn't under 
CPU/memory/IO/network strain, and accessing the file share via SCP/shell 
is fine. Most clients are Windows 7, and are using offline files.

Eventually we gave up debugging, rsynced the share, pointed the DNS 
alias at p-bats (the machine which hosts our group shares) and updated 
samba. This new machine immediately exhibited exactly the same symptom 
(but only for the user share - the group share, which has always been on 
the new machine continued to work fine). The group share is identical, 
except it has create mask = 0775, force create mode = 0660, directory 
mask = 2775,force directory mode = 2770, and veto files is not set.

One thing did change on the 26th - a user was mistakenly created with 
the same UID as a preexisting user. We've deleted the preexisting user 
now, though. Otherwise there are no substantial changes to the user share.

I've noticed that if winbind is stopped the share is as responsive as it 
used to be (on my Linux desktop it takes around 0.477s for: time find 
/mnt/links/user/ash  -type d). Also if I firewall off everything except 
my linux desktop I see similar speeds. On the other hand it can take 
minutes or longer to perform the same command with even just a couple of 
windows machines able to access the server.

Another thing is that we have noticed occasional "port unreachable" 
CLDAP messages from p-cats to a domain controller, (even though the DC 
appeared to be sending a valid response to the same UDP port p-cats just 
sent the CLDAP request from.

Can anybody offer any advice on where we can go next to debug this?

Thanks,

Ashley

testparm looks like:

    Load smb config files from /etc/samba/smb.conf
    Processing section "[user]"
    Processing section "[group.bak]"
    Processing section "[public.bak]"
    Processing section "[system]"
    Processing section "[wpkg.bak]"
    Loaded services file OK.
    Server role: ROLE_DOMAIN_MEMBER

    Press enter to see a dump of your service definitions

    # Global parameters
    [global]
             workgroup = CHESTER-DC
             realm = CHESTER-DC.EXAMPLE.COM
             security = ADS
             map to guest = Bad User
             map untrusted to domain = Yes
             syslog = 0
             log file = /var/log/samba/log.%m
             max log size = 1000
             panic action = /usr/share/samba/panic-action %d
             idmap config chester-dc : range = 1000-999997
             idmap config chester-dc : backend = ad
             idmap config * : range = 1000000-1999999
             idmap config * : backend = tdb
             map hidden = Yes
             map system = Yes
             include = /etc/samba/smb.share.conf


    [user]
             comment = user
             path = /srv/user
             read only = No
             create mask = 0755
             force create mode = 0600
             directory mask = 02755
             force directory mode = 02700
             inherit permissions = Yes
             delete veto files = Yes
             veto files = /$RECYCLE.BIN/


    [group.bak]
             comment = group.bak
             path = /srv/group.bak
             create mask = 0775
             force create mode = 0660
             directory mask = 02775
             force directory mode = 02770
             inherit permissions = Yes


    [public.bak]
             comment = public.bak
             path = /srv/public.bak
             create mask = 0775
             force create mode = 0660
             directory mask = 02775
             force directory mode = 02770
             inherit permissions = Yes


    [system]
             comment = system
             path = /srv/system
             read only = No
             create mask = 0775
             force create mode = 0660
             directory mask = 02775
             force directory mode = 02770
             inherit permissions = Yes
             map archive = No
             map hidden = No
             map system = No
             map readonly = no


    [wpkg.bak]
             comment = wpkg.bak
             path = /srv/public.bak/admin/wpkg
             write list = @it
             create mask = 0775
             force create mode = 0660
             directory mask = 02775
             force directory mode = 02770
             inherit permissions = Yes

At the moment (with only 4 or 5 IT pcs permitted through the firewall) 
It takes around 30 seconds to run "find /mnt/links/user/ash  -type d", 
which contains 976 files, and smbstatus outputs:


    Samba version 4.2.10-Debian
    PID     Username      Group         Machine            Protocol Version
    ------------------------------------------------------------------------------
    7051      ash           Domain Admins  10.4.1.240   (ipv4:10.4.1.240:39646) NT1
    7057      john.         Domain Admins  10.4.1.242   (ipv4:10.4.1.242:65033) SMB3_00
    7057      john.doe      Domain Admins  10.4.1.242   (ipv4:10.4.1.242:65033) SMB3_00
    7689      tim.doe       Domain Admins  10.4.1.245   (ipv4:10.4.1.245:57526) SMB3_00
    7060      ryan          Domain Admins  10.4.1.247   (ipv4:10.4.1.247:54588) SMB2_10

    Service      pid     machine       Connected at
    -------------------------------------------------------
    IPC$         7057   10.4.1.242    Wed Aug 31 16:43:51 2016
    user         7057   10.4.1.242    Wed Aug 31 17:00:02 2016
    user         7060   10.4.1.247    Wed Aug 31 16:43:36 2016
    user         7689   10.4.1.245    Wed Aug 31 16:46:10 2016
    user         7051   10.4.1.240    Wed Aug 31 16:42:41 2016
    user         7057   10.4.1.242    Wed Aug 31 16:42:55 2016

    Registered MSG_REQ_POOL_USAGE
    Registered MSG_REQ_DMALLOC_MARK and LOG_CHANGED
    Locked files:
    Pid          Uid        DenyMode   Access      R/W        Oplock           SharePath   Name   Time
    --------------------------------------------------------------------------------------------------
    7060         10160      DENY_NONE  0x1000a0    RDONLY     NONE             /srv/user   ryan/Private/Documents   Wed Aug 31 16:44:40 2016
    7060         10160      DENY_NONE  0x1000a0    RDONLY     NONE             /srv/user   ryan/Private/Documents   Wed Aug 31 16:44:40 2016
    7060         10160      DENY_NONE  0x1000a0    RDONLY     NONE             /srv/user   ryan/Private/Documents   Wed Aug 31 16:44:40 2016
    7060         10160      DENY_NONE  0x1000a0    RDONLY     NONE             /srv/user   ryan/Private/Documents   Wed Aug 31 16:44:40 2016
    7060         10160      DENY_NONE  0x1000a0    RDONLY     NONE             /srv/user   ryan/Private/Documents   Wed Aug 31 16:44:41 2016
    7060         10160      DENY_NONE  0x1000a0    RDONLY     NONE             /srv/user   ryan/Private/Documents   Wed Aug 31 16:44:41 2016
    7060         10160      DENY_NONE  0x1000a0    RDONLY     NONE             /srv/user   ryan/Private/Documents   Wed Aug 31 16:44:41 2016
    7060         10160      DENY_NONE  0x1000a0    RDONLY     NONE             /srv/user   ryan/Private/Documents   Wed Aug 31 16:44:42 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private/Pictures/Quotation Upddates   Wed Aug 31 16:43:33 2016
    7060         10160      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   ryan/Private/Links   Wed Aug 31 16:43:38 2016
    7060         10160      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   ryan/Private/Start Menu   Wed Aug 31 16:44:15 2016
    7060         10160      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   ryan/Private/Desktop   Wed Aug 31 16:43:42 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private/Desktop   Wed Aug 31 16:43:24 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private/Desktop   Wed Aug 31 16:43:25 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private/Favorites   Wed Aug 31 16:44:29 2016
    7689         10221      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   tim.doe/Private/Desktop   Wed Aug 31 16:57:38 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe   Wed Aug 31 16:45:57 2016
    7057         10002      DENY_NONE  0x80        RDONLY     NONE             /srv/user   john.doe   Wed Aug 31 17:07:26 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private/Desktop/Files For Deletion   Wed Aug 31 16:44:41 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private/Documents   Wed Aug 31 16:43:24 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private/Pictures/Icons/32x32   Wed Aug 31 16:47:33 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private/Pictures   Wed Aug 31 16:44:39 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private/Music   Wed Aug 31 16:43:24 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private/Pictures/Email Safety   Wed Aug 31 16:44:39 2016
    7060         10160      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   ryan/Private/Music   Wed Aug 31 16:44:27 2016
    7060         10160      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   ryan/Private/Music   Wed Aug 31 16:44:28 2016
    7057         10002      DENY_NONE  0x100080    RDONLY     NONE             /srv/user   john.doe/Private/Visual Studio Projects/directory/COWS/obj/Debug/AspnetCompileMerge/Source/fonts/glyphicons-halflings-regular.ttf   Wed Aug 31 17:07:25 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   john.doe/Private   Wed Aug 31 16:46:55 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   .   Wed Aug 31 16:44:04 2016
    7057         10002      DENY_WRITE 0x100081    RDONLY     NONE             /srv/user   .   Wed Aug 31 16:43:32 2016
    7060         10160      DENY_NONE  0x100080    RDONLY     NONE             /srv/user   .   Wed Aug 31 16:43:36 2016
    7689         10221      DENY_NONE  0x100080    RDONLY     NONE             /srv/user   .   Wed Aug 31 16:46:10 2016
    7057         10002      DENY_NONE  0x100081    RDONLY     NONE             /srv/user   .   Wed Aug 31 17:06:33 2016




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