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From: Perry and Lorae Merritt (plmerritt, hypermall dot net) Date: 2001.11.08 - 18.57 MST
X-Mailer: Microsoft Outlook Express 5.50.4522.1200 Does it mention that you can put a printk() in the function and display the read/write value, block number, block size and devno? Huh? Cuz that's what I did after lunch today. Interesting thing when I did that, the blocksize was 4096 which would indicate 16TB volume support in 2.4.9 P ----- Original Message ----- From: "Don jessup" <djessup72, yahoo dot com> To: <antera, cryptofreak dot org> Sent: Thursday, November 08, 2001 1:45 PM Subject: Re: terabyte limit > I believe all of this is explain in Chapter 12 of > the Linux Device Drivers book 2nd Edition. > > --- Perry and Lorae Merritt <plmerritt, hypermall dot net> > wrote: > > I did some looking this morning starting at > > /usr/src/linux/fs/buffer.c looking at the bread() > > function. The bread function is the call in buffer > > cache that either returns a hit or reads the data > > from disk into cache and then returns the hit. It > > calls a function called ll_rw_block which is in the > > block drivers. It talks a bit about LVMs in that > > code. Then a function called bh_present or > > present_bh is called which then calles > > generic_make_request. The last call, calls the > > specific device driver for the device, presumably > > ARVM. > > > > All through the call sequence a structure called > > buffer_head is passed. It's defined in > > /usr/linux/include/linux/fs.h and it contains the > > block size, black address, dev number for the data. > > > > It looks like we can set the blocksize for our > > device. It also looks like the default is 1KB, > > giving a 4TB volume limit. > > > > That's about as far as I got. > > > > P > > ----- Original Message ----- > > From: June Mullins > > To: antera, cryptofreak dot org > > Sent: Wednesday, November 07, 2001 3:16 PM > > Subject: Re: terabyte limit > > > > > > Kevin's note says Reiser is limited by page cache > > to 17592 GB on systems with 32 bit > > addressing (presumably because Reiser uses 4k > > blocks). Isn't that about 17TB, or am I misreading > > the digits? And the LVM and block layer fixes, > > which are below us, allow a logical volume > > to be > 2TB, which it must be to accomodate the > > larger file system. But I don't know what else > > is involved. > > > > June > > > > > > > > > > Perry and Lorae Merritt wrote: > > > > Since I'm pretty sure the block layer is below us > > and since we're dealingwith physical devices that > > are less than a TB, why would we apply fixes tothe > > block layer?I guess what we really need to know is > > how is LVM called from above? What isthe data > > structure that is passed? I guess this is another > > reason for me tohave a linux box here, or at least > > the source code. ;-)In the old days, on AIX, the > > block driver was passed a structure called abuf > > structure. That structure had the device stuff in it > > for the IO. Itcontained the mem address of where to > > put/get the data, which device it wason, and the > > offset on the device. Does Linux use a similar > > mechanism?P----- Original Message -----From: "June > > Mullins" <junemullins, earthlink dot net>To: > > <antera, cryptofreak dot org>Sent: Tuesday, November 06, > > 2001 2:09 PMSubject: Re: terabyte limit > > So, from the note, it sounds like we would just have > > to apply the 64 bitpatch tothe generic block layer > > (and to lvm, if we wind up using it) to getaround > > the 1 or2 Tb limit. However see the link in the > > referenced note to the nextnote aboutLVM extent size > > - that might be something to worry about if we use > > lvmrather than roll our own. JuneDon > > jessup wrote: > > Here is a link to some information on the limit > > > size.http://lists.sistina.com/pipermail/linux-lvm/2001-September/008678.html __________________________________________________Do > > You Yahoo!?Find a job, post your > > resume.http://careers.yahoo.com--This ! > > is the antera mailing list. To unsubscribe, > > emailmajordomo, cryptofreak dot org with message body > > `unsubscribe antera'.Or, for more information, visit > > http://www.cryptofreak.org/. > > --This is the antera mailing list. To unsubscribe, > > emailmajordomo, cryptofreak dot org with message body > > `unsubscribe antera'.Or, for more information, visit > > http://www.cryptofreak.org/. > > --This is the antera mailing list. To unsubscribe, > > emailmajordomo, cryptofreak dot org with message body > > `unsubscribe antera'.Or, for more information, visit > > http://www.cryptofreak.org/. > > > > > > > > __________________________________________________ > Do You Yahoo!? > Find a job, post your resume. > http://careers.yahoo.com > -- > This is the antera mailing list. To unsubscribe, email > majordomo, cryptofreak dot org with message body `unsubscribe antera'. > Or, for more information, visit http://www.cryptofreak.org/. > -- This is the antera mailing list. 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This archive was generated by hypermail 2b30 : 2001.11.09 - 04.02 MST |
