Re: [zfs-discuss] ZFS send/receive while write is enabled on receive side?

[Matthew Ahrens]

On Thu, Dec 9, 2010 at 5:31 PM, Ian Collins  wrote:
>  On 12/10/10 12:31 PM, Moazam Raja wrote:
>> So, is it OK to send/recv while having the receive volume write enabled?

> A write can fail if a filesystem is unmounted for update.

True, but ZFS recv will not normally unmount a filesystem.  It could
if you are receiving an incremental "send -R" stream where the
mountpoint or canmount properties are changed.

If you are accessing a file that is deleted by "zfs recv", then you
will get ESTALE.

--matt
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Re: [zfs-discuss] ZFS send/receive while write is enabled on receive side?

[Ian Collins]

 On 12/10/10 12:31 PM, Moazam Raja wrote:

Hi all, from much of the documentation I've seen, the advice is to set
readonly=on on volumes on the receiving side during send/receive
operations. Is this still a requirement?

I've been trying the send/receive while NOT setting the receiver to
readonly and haven't seen any problems even though we're traversing
and ls'ing the dirs within the receiving volume during the send/recv.

So, is it OK to send/recv while having the receive volume write enabled?


That depends how you define OK!

A ZFS receive will fail (cleanly) if you don't use -F and if you change 
data on the receive side.


A write can fail if a filesystem is unmounted for update.

--
Ian.

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[zfs-discuss] ZFS send/receive while write is enabled on receive side?

[Moazam Raja]

Hi all, from much of the documentation I've seen, the advice is to set
readonly=on on volumes on the receiving side during send/receive
operations. Is this still a requirement?

I've been trying the send/receive while NOT setting the receiver to
readonly and haven't seen any problems even though we're traversing
and ls'ing the dirs within the receiving volume during the send/recv.

So, is it OK to send/recv while having the receive volume write enabled?

-Moazam
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Re: [zfs-discuss] ZFS Prefetch Tuning

[Enda O'Connor]

Hi
I'd certainly look at the sql being run, examine the explain plan and in 
particular SQL_TRACE, TIMED_STATISTICS, and TKPROF, these will really 
highlight issues.


see following for autotrace which can generate explain plan etc.

http://download.oracle.com/docs/cd/B10500_01/server.920/a96533/autotrac.htm


 then the following can really help
SQL>alter session set sql_trace=true;
run sql
SQL>alter session set sql_trace=false  ( this si very important as it 
closes the trace session )

SQL>show parameters show parameters user_dump_dest
 location of output from sql trace

go to user dump dest
you wills ee somethign like
${ORACLE_SID}_ora_6919.trc
tkprof  ${ORACLE_SID}_ora_6919.trc 6919.trc explain=scott/tiger sys=no

ie explain=schema owner and passwrd, if unsure just run
tkprof  ${ORACLE_SID}_ora_6919.trc 6919.trc

this can provide some very informative info, ie unseen ora errors from 
user functions and so on.



read the following to get an idea of how to get at the problematic SQL
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/sql_1016.htm#i26072

I had an interesting issue the other day, where a tablespace was nearing 
100% full on a test DB that isn't properly monitored, and queries stated 
to run really really slow.



Enda


On 09/12/2010 20:22, Jabbar wrote:

Hello Tony,

If the hardware hasn't changed I'd look at the workload on the database
server. If the customer is taking regular statspack snapshots they might
be able to see whats causing the extra activity. They can use AWR or the
diagnostic pack, if they are licensed, to see the offending SQL or
PL/SQL or any hot objects.

However if you want to tune at the ZFS level then the following has some
advice for ZFS and databases
http://www.solarisinternals.com/wiki/index.php/ZFS_for_Databases.

On 9 December 2010 15:48, Tony Marshall mailto:tony.marsh...@oracle.com>> wrote:

Hi All,

Is there a way to tune the zfs prefetch on a per pool basis?  I have
a customer that is seeing slow performance on a pool the contains
multiple tablespaces from an Oracle database, looking at the LUNs
associated to that pool they are constantly at 80% - 100% busy.
Looking at the output from arcstat for the miss % on data, prefetch
and metadata we are getting around 5 - 10 % on data, 50 - 70 % on
prefetch and 0% on metadata.  I am thinking that the majority of the
prefetch misses are due to the tablespace data files.

The configuration of the system is as follows

Sun Fire X4600 M2 8 x 2.3 GHz Quad Core Processor, 256GB Memory
Solaris 10 Update 7
ZFS Arc cache max set to 85GB
4 Zpools configured from a 6540 Storage array

* apps - single LUN (raid 5) recordsize set to 128k, from the
  array, pool contains binaries and application files
* backup - 8 LUNs (varying sizes all from a 6180 array with SATA
  disks) used for storing oracle dumps
* data - 5 LUNs (Raid 10  6 physical drives) recordsize set to
  8k, used for Oracle data files
* logs - single LUN (raid 10 from 6 physical drives) recordsize
  set to 128k, used for Oracle redo log files, temp db, undo db
  and control files.

18 Solaris 10 zones, of which 12 of these are oracle zones sharing
the data and logs pools.

I think that the prefetch will be useful on the apps and backup
pools, however I think that on the data and logs pools this could be
causing issues with the amount of IO that is being caused by the
prefetch and the amount that it is missing in the arcstats could be
the reason why the devices are at 100% busy.  Is there a way to turn
the prefetch off for just a single pool? Also is this something that
can be done online or will it require a reboot to put into effect.

Thanks in advance for your assistance in this matter.

Regards
Tony
--
Oracle 
Tony Marshall | Technical Architect
Phone: +44 118 924 9516  | | | Mobile:
+44 7765 898570 
Oracle Remote Operations Management
United Kingdom

ORACLE Corporation UK Ltd is a company incorporated in England &
Wales | Company Reg. No. 1782505 | Reg. office: Oracle Parkway,
Thames Valley Park, Reading RG6 1RA
Green Oracle  Oracle is committed
to developing practices and products that help protect the environment

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Re: [zfs-discuss] ZFS Prefetch Tuning

[Jabbar]

I've also found this
http://developers.sun.com/solaris/docs/wp-oraclezfsconfig-0510_ds_ac2.pdf

On 9 December 2010 20:22, Jabbar  wrote:

> Hello Tony,
>
> If the hardware hasn't changed I'd look at the workload on the database
> server. If the customer is taking regular statspack snapshots they might be
> able to see whats causing the extra activity. They can use AWR or the
> diagnostic pack, if they are licensed, to see the offending SQL or PL/SQL or
> any hot objects.
>
> However if you want to tune at the ZFS level then the following has some
> advice for ZFS and databases
> http://www.solarisinternals.com/wiki/index.php/ZFS_for_Databases.
>
> On 9 December 2010 15:48, Tony Marshall  wrote:
>
>>  Hi All,
>>
>> Is there a way to tune the zfs prefetch on a per pool basis?  I have a
>> customer that is seeing slow performance on a pool the contains multiple
>> tablespaces from an Oracle database, looking at the LUNs associated to that
>> pool they are constantly at 80% - 100% busy.  Looking at the output from
>> arcstat for the miss % on data, prefetch and metadata we are getting around
>> 5 - 10 % on data, 50 - 70 % on prefetch and 0% on metadata.  I am thinking
>> that the majority of the prefetch misses are due to the tablespace data
>> files.
>>
>> The configuration of the system is as follows
>>
>> Sun Fire X4600 M2 8 x 2.3 GHz Quad Core Processor, 256GB Memory
>> Solaris 10 Update 7
>> ZFS Arc cache max set to 85GB
>> 4 Zpools configured from a 6540 Storage array
>>
>>- apps - single LUN (raid 5) recordsize set to 128k, from the array,
>>pool contains binaries and application files
>>- backup - 8 LUNs (varying sizes all from a 6180 array with SATA
>>disks) used for storing oracle dumps
>>- data - 5 LUNs (Raid 10  6 physical drives) recordsize set to 8k,
>>used for Oracle data files
>>- logs - single LUN (raid 10 from 6 physical drives) recordsize set to
>>128k, used for Oracle redo log files, temp db, undo db and control files.
>>
>> 18 Solaris 10 zones, of which 12 of these are oracle zones sharing the
>> data and logs pools.
>>
>> I think that the prefetch will be useful on the apps and backup pools,
>> however I think that on the data and logs pools this could be causing issues
>> with the amount of IO that is being caused by the prefetch and the amount
>> that it is missing in the arcstats could be the reason why the devices are
>> at 100% busy.  Is there a way to turn the prefetch off for just a single
>> pool? Also is this something that can be done online or will it require a
>> reboot to put into effect.
>>
>> Thanks in advance for your assistance in this matter.
>>
>> Regards
>> Tony
>> --
>> [image: Oracle] 
>> Tony Marshall | Technical Architect
>> Phone: +44 118 924 9516  | | | Mobile: +44
>> 7765 898570 
>> Oracle Remote Operations Management
>> United Kingdom
>>
>> ORACLE Corporation UK Ltd is a company incorporated in England & Wales |
>> Company Reg. No. 1782505 | Reg. office: Oracle Parkway, Thames Valley Park,
>> Reading RG6 1RA
>> [image: Green Oracle]  Oracle is
>> committed to developing practices and products that help protect the
>> environment
>>
>> ___
>> zfs-discuss mailing list
>> zfs-discuss@opensolaris.org
>> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>>
>>
>
>
> --
> Thanks
>
>  A Jabbar Azam
>
>


-- 
Thanks

 A Jabbar Azam
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Re: [zfs-discuss] ZFS Prefetch Tuning

[Jabbar]

Hello Tony,

If the hardware hasn't changed I'd look at the workload on the database
server. If the customer is taking regular statspack snapshots they might be
able to see whats causing the extra activity. They can use AWR or the
diagnostic pack, if they are licensed, to see the offending SQL or PL/SQL or
any hot objects.

However if you want to tune at the ZFS level then the following has some
advice for ZFS and databases
http://www.solarisinternals.com/wiki/index.php/ZFS_for_Databases.

On 9 December 2010 15:48, Tony Marshall  wrote:

>  Hi All,
>
> Is there a way to tune the zfs prefetch on a per pool basis?  I have a
> customer that is seeing slow performance on a pool the contains multiple
> tablespaces from an Oracle database, looking at the LUNs associated to that
> pool they are constantly at 80% - 100% busy.  Looking at the output from
> arcstat for the miss % on data, prefetch and metadata we are getting around
> 5 - 10 % on data, 50 - 70 % on prefetch and 0% on metadata.  I am thinking
> that the majority of the prefetch misses are due to the tablespace data
> files.
>
> The configuration of the system is as follows
>
> Sun Fire X4600 M2 8 x 2.3 GHz Quad Core Processor, 256GB Memory
> Solaris 10 Update 7
> ZFS Arc cache max set to 85GB
> 4 Zpools configured from a 6540 Storage array
>
>- apps - single LUN (raid 5) recordsize set to 128k, from the array,
>pool contains binaries and application files
>- backup - 8 LUNs (varying sizes all from a 6180 array with SATA disks)
>used for storing oracle dumps
>- data - 5 LUNs (Raid 10  6 physical drives) recordsize set to 8k, used
>for Oracle data files
>- logs - single LUN (raid 10 from 6 physical drives) recordsize set to
>128k, used for Oracle redo log files, temp db, undo db and control files.
>
> 18 Solaris 10 zones, of which 12 of these are oracle zones sharing the data
> and logs pools.
>
> I think that the prefetch will be useful on the apps and backup pools,
> however I think that on the data and logs pools this could be causing issues
> with the amount of IO that is being caused by the prefetch and the amount
> that it is missing in the arcstats could be the reason why the devices are
> at 100% busy.  Is there a way to turn the prefetch off for just a single
> pool? Also is this something that can be done online or will it require a
> reboot to put into effect.
>
> Thanks in advance for your assistance in this matter.
>
> Regards
> Tony
> --
> [image: Oracle] 
> Tony Marshall | Technical Architect
> Phone: +44 118 924 9516  | | | Mobile: +44
> 7765 898570 
> Oracle Remote Operations Management
> United Kingdom
>
> ORACLE Corporation UK Ltd is a company incorporated in England & Wales |
> Company Reg. No. 1782505 | Reg. office: Oracle Parkway, Thames Valley Park,
> Reading RG6 1RA
> [image: Green Oracle]  Oracle is
> committed to developing practices and products that help protect the
> environment
>
> ___
> zfs-discuss mailing list
> zfs-discuss@opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>
>


-- 
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 A Jabbar Azam
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[zfs-discuss] ZFS Prefetch Tuning

[Tony Marshall]

  
  
Hi All,

Is there a way to tune the zfs prefetch on a per pool basis?  I have
a customer that is seeing slow performance on a pool the contains
multiple tablespaces from an Oracle database, looking at the LUNs
associated to that pool they are constantly at 80% - 100% busy. 
Looking at the output from arcstat for the miss % on data, prefetch
and metadata we are getting around 5 - 10 % on data, 50 - 70 % on
prefetch and 0% on metadata.  I am thinking that the majority of the
prefetch misses are due to the tablespace data files.

The configuration of the system is as follows

Sun Fire X4600 M2 8 x 2.3 GHz Quad Core Processor, 256GB Memory
Solaris 10 Update 7
ZFS Arc cache max set to 85GB
4 Zpools configured from a 6540 Storage array

  apps - single LUN (raid 5) recordsize set to 128k, from the
array, pool contains binaries and application files
  backup - 8 LUNs (varying sizes all from a 6180 array with SATA
disks) used for storing oracle dumps
  data - 5 LUNs (Raid 10  6 physical drives) recordsize set to
8k, used for Oracle data files
  logs - single LUN (raid 10 from 6 physical drives) recordsize
set to 128k, used for Oracle redo log files, temp db, undo db
and control files.

18 Solaris 10 zones, of which 12 of these are oracle zones sharing
the data and logs pools.

I think that the prefetch will be useful on the apps and backup
pools, however I think that on the data and logs pools this could be
causing issues with the amount of IO that is being caused by the
prefetch and the amount that it is missing in the arcstats could be
the reason why the devices are at 100% busy.  Is there a way to turn
the prefetch off for just a single pool? Also is this something that
can be done online or will it require a reboot to put into effect.

Thanks in advance for your assistance in this matter.

Regards
Tony
-- 
  
  Tony Marshall | Technical Architect
Phone: +44 118 924 9516
| | | Mobile: +44 7765 898570

Oracle Remote Operations Management
United Kingdom
  
  ORACLE Corporation UK
Ltd is a company incorporated in England & Wales | Company
Reg. No. 1782505 | Reg. office: Oracle Parkway, Thames Valley
Park, Reading RG6 1RA
  
  
  Oracle is committed to developing practices and
products that help protect the environment
  

  

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Re: [zfs-discuss] How many files & directories in a ZFS filesystem?

[Peter Tribble]

On Thu, Dec 9, 2010 at 1:23 PM, David Strom  wrote:
> Looking for a little help, please.  A contact from Oracle (Sun) suggested I
> pose the question to this email.
>
> We're using ZFS on Solaris 10 in an application where there are so many
> directory-subdirectory layers, and a lot of small files (~1-2Kb) that we ran
> out of inodes (over 30 million!).
>
> So, the zfs question is, how can we see how many files & directories have
> been created in a zfs filesystem?  Equivalent to "df -o i" on a UFS
> filesystm.

If you have gnu df, (it's in /opt/sfw/bin/gdf if you've installed the companion
CD), then that supports the -i flag.

Alternatively parse the output from df -g. I have a horrid script that does
something like that, fragment here:

echo "Filesystemiused   ifree   %iused  Mounted on"
for ZF in ${FSLIST}
do
OUT=`/usr/sbin/df -g ${ZF} | awk -F: '{print $NF}'`
NFILES=`echo $OUT | awk '{print $15}'`
NFREE=`echo $OUT | awk '{print $18}'`
NUSED=$(($NFILES-$NFREE))
NPERC=$(((100*NUSED)/NFILES))
SPACE=`/usr/sbin/df -k ${ZF} | nawk '/%/{print $3}'`
echo "${ZF} $NUSED  $NFREE  ${NPERC}%   ${ZF}"
echo "  average $(($SPACE/$NUSED))k"
done

ZFS goes up to ridiculous number of files. Here's one of ours
which has a fair number:

Filesystem  iused   ifree   %iused  Mounted on
/images/fred 140738056   36000718887 0%  /images/fred
average 11k

I've never seen ZFS run out of inodes, though.

-- 
-Peter Tribble
http://www.petertribble.co.uk/ - http://ptribble.blogspot.com/
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Re: [zfs-discuss] How many files & directories in a ZFS filesystem?

[Tomas Ögren]

On 09 December, 2010 - David Strom sent me these 0,7K bytes:

> Looking for a little help, please.  A contact from Oracle (Sun)  
> suggested I pose the question to this email.
>
> We're using ZFS on Solaris 10 in an application where there are so many  
> directory-subdirectory layers, and a lot of small files (~1-2Kb) that we  
> ran out of inodes (over 30 million!).
>
> So, the zfs question is, how can we see how many files & directories  
> have been created in a zfs filesystem?  Equivalent to "df -o i" on a UFS  
> filesystm.
>
> Short of doing a find  | wc.

GNU df can show, and regular Solaris could too but chooses not to.
statvfs() should be able to report as well. In ZFS, you will run out of
inodes at the same time as you run out of space.

/Tomas
-- 
Tomas Ögren, st...@acc.umu.se, http://www.acc.umu.se/~stric/
|- Student at Computing Science, University of Umeå
`- Sysadmin at {cs,acc}.umu.se
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Re: [zfs-discuss] very slow boot: stuck at mounting zfs filesystems

[Frank Van Damme]

2010/12/8  :
> To explain further the  slow delete problem:
>
> It is absolutely critical for zfs to manage the incoming data rate.
> This is done reasonably well for write transactions.
>
> Delete transactions, prior to dedup, were very light-weight, nearly free,
> so these are not managed.
>
> Because of dedup,  deletes become rather expensive, because they introduce a
> substantial seek penalty. Mostly because the need to update the dedupe
> meta data (reference counts and such)
>
> The mechanism of the problem:
> 1) Too many delete transactions are accepted into the
> open transaction group.
>
> 2) When this txg comes up to be synced to disk, the sync takes a very long
> time.
> ( instead of a healthy 1-2 seconds, minutes, hours or days)

Ok, had to look that one up, but the fog starts clearing up.
I reckon in zfs land, a command like "sync" has no effect at all?

> 3) Because the open txg can not be closed while the sync of a previous txg
> is in progress, eventually we run out of buffer space in the open txg, and all
> input is severely throttled.
>
> 4) Because of (3) other bad things happen, like the arc tries to shrink,
> memory shortage, making things worse.

Yes... I see... speaking of which: the arc size on my system would be
1685483656 bytes - that's 1.6 GB in a system with 6 GB, with 3942 MB
allocated to the kernel (dixit mdb's ::memstat module). So can i
assume that the better part of the rest is allocated in buffers that
needlessly fill up over time? I'd much rather have the memory used for
ARC :)

> 5) Because delete-s persist across reboots, you are unable to mount your
> pool
>
> Once solution is booting into maintenance mode, and renaming the zfs cache
> file (look in /etc/zfs, I forget the name at the moment)
> You can then boot up and import your pool. The import will take a long time
> but meanwhile you are up and can do other things.
> At that point you have the option of getting rid of the pool and starting
> over
> ( possibly installing a better kernel and starting over)..
> After update, and import, update your pool to the current pool version
> and life will be much better.

By now, the system booted up. It has taken quit a few hours though.
This system is actually running Nexenta but I'll see if I can upgrade
the kernel.

> I hope this helps, good luck

It clarified a few things. Thank you very much. There are one or two
things I still have to change on this system it seems...

> In addition, there was virtual memory related bug (allocating one of the zfs
> memory caches with the wrong object size) that would cause other
> components to hang, waiting for memory allocations.
>
> This was so bad in earlier kernels that systems would become unresponsive
> for
> a potentially very long time ( a phenomenon known as "bricking").
>
> As I recall a lot fo fixes came in in the 140 series kernels to fix this.
>
> Anything 145 and above should be OK.

I'm on 134f. No wonder.

-- 
Frank Van Damme
No part of this copyright message may be reproduced, read or seen,
dead or alive or by any means, including but not limited to telepathy
without the benevolence of the author.
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[zfs-discuss] How many files & directories in a ZFS filesystem?

[David Strom]

Looking for a little help, please.  A contact from Oracle (Sun) 
suggested I pose the question to this email.


We're using ZFS on Solaris 10 in an application where there are so many 
directory-subdirectory layers, and a lot of small files (~1-2Kb) that we 
ran out of inodes (over 30 million!).


So, the zfs question is, how can we see how many files & directories 
have been created in a zfs filesystem?  Equivalent to "df -o i" on a UFS 
filesystm.


Short of doing a find  | wc.

TIA.

--
David Strom
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Re: [zfs-discuss] Faster than 1G Ether... ESX to ZFS

[erik.ableson]

On 9 déc. 2010, at 13:41, Edward Ned Harvey wrote:

>> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
>> boun...@opensolaris.org] On Behalf Of Edward Ned Harvey
>> 
>> Also, if you have a NFS datastore, which is not available at the time of
> ESX
>> bootup, then the NFS datastore doesn't come online, and there seems to be
>> no
>> way of telling ESXi to make it come online later.  So you can't auto-boot
>> any guest, which is itself stored inside another guest.
> 
> Someone just told me about
>   esxcfg-nas -r
> So yes, it is possible to make ESX remount the NFS datastore in order to
> boot the other VM's.  The end result should be something which is faster
> than 1G ether, but not as fast as IB, FC, or 10G.

I've got a similar setup running here - with the Nexenta VM set to auto-start, 
you have to wait a bit for the VM to startup until the NFS datastores become 
available, but the actual mount operation from the ESXi side is automatic. I 
suppose that if you played with the startup delays between virtual machines you 
could get everything to start unattended once you know how long it takes for 
the NFS stores to become available.

Combined with send/recv to another box it's an affordable disaster recovery 
solution. And to squeeze every bit of performance out of the configuration, you 
can use VMDirectPath to present the HBA to your storage VM (just remember to 
add another card to boot ESXi or store a VMFS volume for vmx and swap files.

Erik
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Re: [zfs-discuss] Faster than 1G Ether... ESX to ZFS

[Edward Ned Harvey]

> From: zfs-discuss-boun...@opensolaris.org [mailto:zfs-discuss-
> boun...@opensolaris.org] On Behalf Of Edward Ned Harvey
> 
> Also, if you have a NFS datastore, which is not available at the time of
ESX
> bootup, then the NFS datastore doesn't come online, and there seems to be
> no
> way of telling ESXi to make it come online later.  So you can't auto-boot
> any guest, which is itself stored inside another guest.

Someone just told me about
esxcfg-nas -r
So yes, it is possible to make ESX remount the NFS datastore in order to
boot the other VM's.  The end result should be something which is faster
than 1G ether, but not as fast as IB, FC, or 10G.

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Re: [zfs-discuss] very slow boot: stuck at mounting zfs filesystems

[Frank Van Damme]

2010/12/8 taemun :
> Dedup? Taking a long time to boot after hard reboot after lookup?
>
> I'll bet that it hard locked whilst deleting some files or a dataset that
> was dedup'd. After the delete is started, it spends *ages* cleaning up the
> DDT (the table containing a list of dedup'd blocks). If you hard lock in the
> middle of this clean up, then the DDT isn't valid, to anything. The next
> mount attempt on that pool will do this operation for you. Which will take
> an inordinate amount of time. My pool spent eight days (iirc) in limbo,
> waiting for the DDT cleanup to finish. Once it did, it wrote out a shedload
> of blocks and then everything was fine. This was for a zfs destroy of a
> 900GB, 64KiB block dataset, over 2x 8-wide raidz vdevs.

Eight days is just... scary.
Ok so basically it seems you can't have all the advantages of zfs at
once. No more fsck, but if you have a deduplicated pool the kernel
will still consider it as "unclean" if you have a crash or unclean
shutdown?

I am indeed nearly continously deleting older files because each day a
mass of files gets written to the machine (and backups rotated). Is it
in some way possible to do the cleanup in smaller increments so the
amount of cleanup work to do when you (hard)reboot is smaller?

> Unfortunately, raidz is of course slower for random reads than a set or
> mirrors. The raidz/mirror hybrid allocator available in snv_148+ is somewhat
> of a workaround for this, although I've not seen comprehensive figures for
> the gain it gives
> - http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6977913



-- 
Frank Van Damme
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