Hi Terry,
Your observation makes me speechless...
I have not done thorough tests on this issue, however this blocksize
limitation has been formally published by EMC/Legato and acknowledged by
Microsoft.
Please see below a short description from the KB907418 article in the MS
knowledge base:
CAUSE
This problem occurs because Windows Server 2003 with SP1 limits block
sizes to 64 KB during a tape transfer. This limitation may limit the
performance of high performance tape drives that use larger block sizes.
Hotfix 873422 also applies this limitation.
Regards,
Itzik
-----Original Message-----
From: lemons_terry AT emc DOT com [mailto:lemons_terry AT emc DOT com]
Sent: Wednesday, July 26, 2006 02:56
To: Itzik Meirson
Cc: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: RE: [Networker] HELP - BRP
Hi Itzik
Thanks very much for making us all aware of KB907418; I hadn't heard of
it,
though I am all-too-familiar with Windows environment's propensity to
have
block size mutations between NetWorker and the tape device.
I have a Windows 2003 SP 1 system running the latest Microsoft Update
stuff.
I have a Qlogic QLA2342 FC adapter using driver v9.0.0.2. I do not yet
have
the modified tape.sys file mentioned in KB907418.
I labeled and wrote to a SDLT320 tape on my Windows 2003 SP 1 system.
NetWorker uses a block size of 128 KB to write to the SDLT 320 (Davina
Treiber provided the NetWorker device block size list earlier in this
thread). I then mounted this tape on a Linux system, and used the 'mt'
and
'dd' commands to determine the block size used:
nsrjb -lnvS1 -f /dev/nst0 - have nsrjb load [-l] the tape in slot
1
in drive /dev/nst0, but NOT mount it
[-n];
this allows other programs to use the
tape drive
mt -f /dev/nst0 rewind - position the tape at BOT
mt -f /dev/nst0 status - just for giggles
dd if=/dev/nst0 bs=32k | od -tc - dd reads one 32KB block (the first
NetWorker tape
label) and od dumps the data in text
format
dd if=/dev/nst0 bs=32k | od -tc - dd reads one 32KB block (the second
NetWorker tape
label) and od dumps the data in text
format
dd if=/dev/nst0 bs=XXk of=/dev/nst0 - dd uses the specified block size
to
read
the tape. If the wrong block size
is
used,
dd returns an error (I got 'cannot
allocate memory')
When I replaced XX above with '128', the dd command failed, telling me
that
128 KB blocks had NOT been used. Sure enough, I tried '64', and dd
could
read the blocks.
Next, I used regedit on the Windows 2003 SP 1 system, and added the
following:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\ql2300\Parameters\D
evic
e\MaximumSGList REG_DWORD: 0xFF
And rebooted. I repeated the same test, and found that 128 KB blocks
had
been used to write the tape. I didn't expect this, as I expected the
problem in KB907418 to limit block size to 64 KB.
Hope this helps someone!
tl
-----Original Message-----
From: Legato NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU]
On
Behalf Of Itzik Meirson
Sent: Monday, May 15, 2006 3:54 PM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: Re: [Networker] HELP - BRP
Importance: High
I would bet your original backup server is not Win2k3 SP1.
Win2k SP1 has introduced a limit on the maximum block size.
If at your DR site you have Win2k3 SP1 I would suggest either to remove
SP1 or apply the emergency fix MS has provided to revert this
limitation.
This is described in MS KB907418.
Itzik
-----Original Message-----
From: Legato NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU]
On Behalf Of Scalise, Kathleen (NSTS.JAX)
Sent: Monday, May 15, 2006 18:03
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: Re: [Networker] HELP - BRP
Davina:
Our library here is fibre attached and the drive at our BRP site is a
direct connect stand alone.
Kathleen Scalise
Asst. Vice President
Network Services and Technology Support
Merrill Lynch - Jacksonville, Florida
Phone: 904.218.5139
Fax: 904.218.5445
kathleen_scalise AT ml DOT com
-----Original Message-----
From: Davina Treiber [mailto:DavinaTreiber AT PeeVRo.co DOT uk]
Sent: Monday, May 15, 2006 10:18 AM
To: Legato NetWorker discussion; Scalise, Kathleen (NSTS.JAX)
Subject: Re: [Networker] HELP - BRP
Scalise, Kathleen (NSTS.JAX) wrote:
> The device block size in Networker Admin 'Configuration' tab for the
> drive is "handler default". Is there where I set it to 128K??
>
> In the 'Volume' tape of the device it reflect 128K. Below the Record
> size = 131072 bytes = 128K?
>
> Checking my main backup server that the tape was created on, it is the
> same.
>
Kathleen,
The "More data is available" error messages definitely indicates a block
size mismatch, telling you that the blocksize of the data on the tape is
larger than you can read on your DR server.
If you have not changed the block size (by setting an environment
variable on your main server), then NetWorker will be using its
defaults, so you are looking slightly in the wrong place. The most
likely explanation is the the hardware at your DR site cannot read data
written with the NetWorker LTO-3 default blocksize due to a limitation
of the driver for the HBA. I would guess that the HBA in use at your DR
site is not the same as your main site, or is perhaps using a different
driver or different servicepack.
To resolve this you will need to either change the HBA or change the
driver on your DR site. Another approach is to reduce the block size on
your main site to match the limitation on your DR site, however this
does not help you to read this particular tape, and this approach could
result in a performance degradation.
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