From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: tuhs-bounces@minnie.tuhs.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,HTML_FONT_LOW_CONTRAST, HTML_MESSAGE,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.2 Received: from minnie.tuhs.org (minnie.tuhs.org [45.79.103.53]) by inbox.vuxu.org (OpenSMTPD) with ESMTP id bb3eb773 for ; Mon, 15 Oct 2018 21:02:42 +0000 (UTC) Received: by minnie.tuhs.org (Postfix, from userid 112) id 905009E992; Tue, 16 Oct 2018 07:02:41 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 1DB3A9E6F2; Tue, 16 Oct 2018 07:02:02 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id B3CA39E6F2; Tue, 16 Oct 2018 07:01:00 +1000 (AEST) Received: from mail-oi1-f174.google.com (mail-oi1-f174.google.com [209.85.167.174]) by minnie.tuhs.org (Postfix) with ESMTPS id 0C8019E708 for ; Tue, 16 Oct 2018 07:00:55 +1000 (AEST) Received: by mail-oi1-f174.google.com with SMTP id l197-v6so16238225oib.8 for ; Mon, 15 Oct 2018 14:00:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ccc.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=t6fFOwSRQNZ2zrW9uaM699UUjtgLc1Ijgm1YXauQgXQ=; b=o8uN0Whihe6oC0+aPdMCLc028egRnWtgw+xqoIsZEZvwMvnTYB50ICC3ILo9xbxwHD Pkgg5msJu8qMAqMCi4cF5QklvsbL1u/Fat0Q3r/mih6/Fo1fme96R3netIPq5WjsxNF6 x1Jtl+OwHN2c4fa308/GYZHeXDryereBu4Fqo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=t6fFOwSRQNZ2zrW9uaM699UUjtgLc1Ijgm1YXauQgXQ=; b=OG0Q8/5bvxN2g6KXd/rzoNgwRpa2KeelBqN3StC49uk612psMVr5BslSdBUjp7tU5Z 5juBK2oIFQkq6axkAaH+TU2hdxx6Q6Vnrt5VuBdERuQxjysF/BziGAcpisdtzeZBwYbl kCE7K4eNg4HNbuaS2J44xRe2sftgzoJ5eR8bGYKhppVBaqAHY5eqkrqe6su/O3y8d3jP sSXHXLPsNQVdg2Fkl3fxI2SMfp+0TJ6gfeqKaB1uQ6+cuJ3qRDz7GbvDtp7A2m1nj0WH kqBmiB7LKULWC4HHmcXtvS2mLnp+QhoX2QEqns1+6pDcj8bRDQqSSFcCykZDd9Ge2f8l ueEA== X-Gm-Message-State: ABuFfojP4X3kLmNLpIGMznjLssIOner39+xgsUG6svz9Bp3wmpyVt2Es LR9xVfVFV0O5/d4M+P/HurbKlBAUhiFNBXqWnOGkZhZhkAU= X-Google-Smtp-Source: ACcGV63abSsqRB8dpi8ep2u/9lYUfGQreQO/DRCD3Lgro0bngtJzIYufSw8Ml6PuVqgFysdllhvQ+2iAPo6fwtjIyaQ= X-Received: by 2002:aca:a618:: with SMTP id p24-v6mr5821894oie.44.1539637254228; Mon, 15 Oct 2018 14:00:54 -0700 (PDT) MIME-Version: 1.0 References: <20181015195622.GB25749@minnie.tuhs.org> In-Reply-To: <20181015195622.GB25749@minnie.tuhs.org> From: Clem Cole Date: Mon, 15 Oct 2018 17:00:27 -0400 Message-ID: To: Warren Toomey Content-Type: multipart/alternative; boundary="0000000000009f210105784abb7e" Subject: Re: [TUHS] Ultrix Tape: Block Size? X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: The Eunuchs Hysterical Society , cctalk@classiccmp.org Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" --0000000000009f210105784abb7e Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Be careful, TK-50 is different than 9-track. It's a streamer tape like QIC, 4mm and 8mm. The blocking is done under the covers by the HW and the blovk size if just how a DMA is done. I recommend that you pre-fetch the read with dd or double-dd setting ibs=3D64k, obs=3D20b and conv=3Dsync and = pipe the output to the reader (tar/cpio or the like) [if that fails try obs=3D1b]. This should work well as can (TK-50 overall suck - don't set your hopes high on anything with them -- they were DECtape from a realiabilty standpoint, they were different from the reset of the world, the performance was poor and they were expensive). Anyway, by using dd or the like a front end, it will allow the read streamer to read as fast as it can. The problem is that the way it works under the cover does not shine with traditional UNIX I/O. BTW: ibs of anything more than 64K on a VAX (or PDP-11) will not help because of the dma size on the Unibus caps DMA read/writes at 64K. On a PMAX or (under Tru64 on a Alpha), you can try using really large ibs sizes depending on your physical memory size. BTW: What will help the most is actually finding a copy of the old double-dd program (from the UUNET archives) which forks off two child procees to perform the actual I/O and alternates between the two processes via pipe between them and controller - so one dd process is reading when the other dd process is writing. [It used to be called: ddd before the Gnu guys grabbed that name for the debugger]. The command line might be something like: ddd ibs=3D64k obs=3D20b | tar xvpf - FWIW: I wrote a version of a fast dd years ago that used pthreads and a semaphore that I should still have kicking around. At one point when I was dealing with streamer tapes for backup, I definitely ran it on Tru64 and FreeBSD, but I've forgotten where Ultrix fell. =E1=90=A7 On Mon, Oct 15, 2018 at 4:01 PM Warren Toomey wrote: > All, I received this request from Matthew who isn't subscribed to either > the TUHS or cctalk lists. He knows how to read the lists archives. Many > thanks for any help you can provide. > Cheers, Warren > > ----- Forwarded message from Matthew Whitehead ----- > > Date: Mon, 15 Oct 2018 08:25:39 -0400 > From: Matthew Whitehead > Subject: Ultrix Tape Blocks > > Warren, > I wonder if you can give me a referral. I want to install Ultrix-32 > on my MicroVAX II using the ancient TK-50 tape drive. I know the tape > files are on your archive, but I need to know the block size for each > of the many files; it can vary a lot. > Who might be able to help me with this? > Matthew Whitehead > > ----- End forwarded message ----- > --0000000000009f210105784abb7e Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Be careful, TK-50 is different than 9-track.=C2=A0 It&#= 39;s a streamer tape like QIC, 4mm=C2=A0and=C2=A08mm.=C2=A0 =C2=A0The block= ing is done under the covers by the HW and the blovk size if just how a DMA= is done.=C2=A0 I recommend that you pre-fetch the read with dd or double-d= d setting ibs=3D64k, obs=3D20b and conv=3Dsync and pipe the output to the r= eader (tar/cpio=C2=A0or the like) [if that fails try obs=3D1b].=C2=A0 =C2= =A0This should work well as can (TK-50 overall suck - don't set your ho= pes high on anything with them -- they were DECtape from a realiabilty=C2= =A0standpoint, they were different from the reset of the world, the perform= ance was poor and they were expensive).

Anyway, by usi= ng dd or the like a front end, it will allow the read streamer to read as f= ast as it can.=C2=A0 The problem is that the way it works under the cover d= oes not shine with traditional UNIX I/O.=C2=A0 BTW: ibs=C2=A0of anything mo= re than 64K on a VAX (or PDP-11) will not help because of the dma=C2=A0size= on the Unibus=C2=A0caps DMA read/writes at 64K.=C2=A0 =C2=A0On a PMAX or (= under Tru64 on a Alpha), you can try using really large ibs=C2=A0sizes depe= nding on your physical memory size.

BTW: What wi= ll help the most is actually finding a copy of the old double-dd program (f= rom the UUNET archives) which forks off two child procees=C2=A0to perform t= he actual I/O and alternates between the two processes via pipe between the= m and controller - so one dd process is reading when the other dd process i= s writing.=C2=A0 [It used to be called: ddd=C2=A0before the Gnu guys grabbed that name for the debu= gger].=C2=A0 =C2=A0The command line might be something like:=C2=A0 =C2=A0ddd=C2=A0ibs=3D64k obs=3D20b | tar xvpf = -=C2=A0

FWIW:=C2=A0 I wrote a version of a fast= dd years ago that used pthreads and a semaphore that I should still have k= icking around.=C2=A0 =C2=A0At one point when I was dealing with=C2=A0stream= er tapes for backup, I definitely ran it on Tru64 and FreeBSD, but =C2=A0I&= #39;ve forgotten where Ultrix fell.
3D""=E1=90=A7
On Mon, Oct 15, 2018 at 4:01 P= M Warren Toomey <wkt@tuhs.org> wr= ote:
All, I received this request f= rom Matthew who isn't subscribed to either
the TUHS or cctalk lists. He knows how to read the lists archives. Many
thanks for any help you can provide.
Cheers, Warren

----- Forwarded message from Matthew Whitehead -----

Date: Mon, 15 Oct 2018 08:25:39 -0400
From: Matthew Whitehead
Subject: Ultrix Tape Blocks

=C2=A0 =C2=A0Warren,
=C2=A0 =C2=A0 =C2=A0I wonder if you can give me a referral. I want to insta= ll Ultrix-32
=C2=A0 =C2=A0on my MicroVAX II using the ancient TK-50 tape drive. I know t= he tape
=C2=A0 =C2=A0files are on your archive, but I need to know the block size f= or each
=C2=A0 =C2=A0of the many files; it can vary a lot.
=C2=A0 =C2=A0Who might be able to help me with this?
=C2=A0 =C2=A0Matthew Whitehead

----- End forwarded message -----
--0000000000009f210105784abb7e--