topic Re: Extended File Cache (XFC) may cause data corruption in Operating System - OpenVMS

Extended File Cache (XFC) may cause data corruption

Hejib — Mon, 15 Oct 2007 13:57:02 GMT

We are now on Open VMS 7.3-2. Our database support team have found an info on Oracle Metalink which says

"**Warning OpenVMS 7.3**

VMS 7.3 Extended File Cache (XFC) may cause data corruption.

There is a bug in the OpenVMS 7.3 Extended File Cache (XFC) software that may cause data corruption.
XFC is controlled by the sysgen parameter vcc_flags.

By default, XFC is enabled in VMS 7.3. The workaround is to set vcc_flags to 1.

The OpenVMS ECO VMS73_XFC-V0200 (or later) should be applied to resolve this issue. "

We are on Open VMS 7.3-2. From the first read it looks like there was an issue with Open VMS 7.3.

Does anyone know if this has been resolved in 7.3-2 now. VCC_FLAGS is set to 2 by default. Is there ECO available if there still a problem. If not is it safe to leave it at 2.

Re: Extended File Cache (XFC) may cause data corruption

Jess Goodman — Mon, 15 Oct 2007 14:13:49 GMT

This problem was fixed in 7.3-2.
However it is a usually good idea to apply the latest ECO Update kit.

Re: Extended File Cache (XFC) may cause data corruption

Hein van den Heuvel — Mon, 15 Oct 2007 14:24:58 GMT

Fixed in 7.3-2

You really want XFC enabled.
It is extensively used in production for 7.3-2 and beyond.

It tends to be a night-and-day difference in performance, in your favor.

VCC was a teaser, XFC is the real thing.

Cheers,
Hein.

Re: Extended File Cache (XFC) may cause data corruption

Robert Brooks_1 — Mon, 15 Oct 2007 14:53:11 GMT

We are now on Open VMS 7.3-2.

--

Congrats -- I hope this is not a production environment. If it is a production system, I hope you are paying for prior version support (PVS). V7.3-2 went off "standard support" at the end of 2006.

While the reality may not be that dire, since we'll still take support calls for V7.3-2, it's likely that we won't be particularly motivated to fix a problem that's been solved in a later release (unless you're a PVS customer).

(And yes, I know that we are still releasing patch kits for V7.3-2. I've not verified that they're available to the general public, but I do see an indication that the kits are being built.)

Is there a reason you've not upgraded to V8.3
or V8.2?

As others have said, please install the latest patch kits, or at least the latest
UPDATE kit for V7.3-2. This is especially important if you are using fibre channel storage or host-based volume shadowing.

-- Rob

Re: Extended File Cache (XFC) may cause data corruption

Hoff — Mon, 15 Oct 2007 14:54:52 GMT

V7.3-1 and later include V7.3 XFC V2.0, and various other releases.

Here's the secret incantation for determining this:

http://h18000.www1.hp.com/support/asktima/operating_systems/CHAMP_SRC020912000760.html
http://h18000.www1.hp.com/support/asktima/operating_systems/CHAMP_SRC031216000648.html

The above-series articles are apparently no longer being actively updated, so you'll want to look here for the ECO listings for V7.3-2:

ftp://ftp.itrc.hp.com/openvms_patches/alpha/V7.3-2/ALPHA_V732_MASTER_ECO_LIST.txt

Finding the articles involves some known and unique keywords derived from the titles of this series of articles, and a trip through the older ITRC James search engine.

Regardless of this or other similarly old notes, you want XFC enabled. It works. It works fast. (The older VIOC cache has had its own and varied problems over the years, too, and it's significantly slower than XFC.) And I'd be surprised if Oracle didn't support it now, given the effort and speed involved. (But do check with Oracle for their list of required ECO kits and support requirements.)

And FWIW, V7.3-2 is itself getting rather old and semi-crufty. ECO notices for V7.3 are, well, fully old and fully crufty.

Re: Extended File Cache (XFC) may cause data corruption

Hejib — Wed, 17 Oct 2007 02:49:52 GMT

Thank you all for all the advise.

Re: Extended File Cache (XFC) may cause data corruption

Hejib — Wed, 17 Oct 2007 02:52:14 GMT

Excellent responses from all.