RE: [gentoo-user] Max Number of Partitions
-Original Message- From: Boyd Stephen Smith Jr. [mailto:[EMAIL PROTECTED] Sent: 13 February 2006 01:32 To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] Max Number of Partitions Um, activate the vg in partial mode and lvols on the good disk will still be accessible -- I think even writable, but I could be wrong on that point. I'm not sure if that's in the standard lvm startup scripts on gentoo, but my initrd includes vgscan -P; vgchange -Pay. Nah, too dangerous for me. I use multiple Volume Groups. Then you can't have a lv that's bigger than a single pv or migrate data between pvs (to switch them out or w/e) using pvmove. You are seriously crippling the usefulness of lvm if you always use a 1 pv = 1 vg rule. Thank you all for the responses! It's taken me sometime to check my mail and they've piled up. :) Two quick Q's: Current partitions 1, 13, 14, 15 and 16 are NTFS. As I understand it LVM is a software solution that works happily with Linux. What happens when my other half tries to boot into WinXP? Are we going to have a major domestic because I hosed *her* computer? I believe Alexander mentioned it, but the reason I have placed directories like /usr/portage into different partitions is to minimise data fragmentation. How does this work in an LVM set up? -- Regards, Mick -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
Michael Kintzios wrote: Two quick Q's: Current partitions 1, 13, 14, 15 and 16 are NTFS. As I understand it LVM is a software solution that works happily with Linux. Yes. And only Linux - meaning, that if you'd boot FreeBSD or Solaris, you won't be able to use your filesystems. What happens when my other half tries to boot into WinXP? She won't be able to access the Linux filesystems. Are we going to have a major domestic because I hosed *her* computer? No. Windows will only see one partition - the partition holding the physical volume (PV) which contains your volume group (VG) which, in turn, contains the logical volumes (LV) on which you'll, finally *G*, have your filesystems. I believe Alexander mentioned it, but the reason I have placed directories like /usr/portage into different partitions is to minimise data fragmentation. I'm talking about a different kind of fragmentation. With LVM, logical volumes (partitions) don't have to be consecutive. Indeed, most of the time they won't be. So, suppose you create lvol1 and lvol2. Now you wish to extend lvol1. What will happen is, that the phsyical extents (blocks) for lvol1 are in front of and behind lvol2 (simply put). How does this work in an LVM set up? Filesystems don't see that they are on logical volumes. This means, that the filesystem fragmentation will happen just as as it normally does. Alexander Skwar -- God is subtle, but he is not malicious. -- Albert Einstein -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
On Monday 13 February 2006 08:54, Michael Kintzios [EMAIL PROTECTED] wrote about 'RE: [gentoo-user] Max Number of Partitions': Current partitions 1, 13, 14, 15 and 16 are NTFS. As I understand it LVM is a software solution that works happily with Linux. What happens when my other half tries to boot into WinXP? Are we going to have a major domestic because I hosed *her* computer? Windows will not be able to see LVs; These will have to remain as partitions or you can use the windows equivalent of LVM. It's something like dynamic disk management or dynamic volume manager... I don't use windows much. I believe Alexander mentioned it, but the reason I have placed directories like /usr/portage into different partitions is to minimise data fragmentation. How does this work in an LVM set up? The filesystem will see a LV the same way it sees a partition, as a single contiguous block device. Filesystem level fragmentation will happen as normal on this block device. However, LVM does introduce the possibility for the LV itself to become fragmented. You can prevent this by marking the LV(s) as contiguous, but that will prevent you from extending the LV in some cases. Generally LV fragmentation is much less of a problem because LVs change size less often than the files on the filesystems they host change size. -- Boyd Stephen Smith Jr. [EMAIL PROTECTED] ICQ: 514984 YM/AIM: DaTwinkDaddy -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
Francesco Riosa wrote: Someone, somewhere, one time told me that lvm could address that in some manner but I've never seen how. Easy - with LVM, you (ideally) don't create any partitions. Instead, you create so called logical volumes (LVs). On those LVs, you the filesystems. Alexander Skwar -- Yes, many primitive people still believe this myth...But in today's technical vastness of the future, we can guess that surely things were much different. - The Firesign Theater -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
Shawn Haggett wrote: LVM would indeed be a solution. Instead of creating many disk partitions, you would simply create one large one the size of the disk. Yes, you could. But if you go that way, you don't have to create any partitions at all. Instead, you can also use /dev/hda with LVM. Then using LVM create as many virtual partitions as you need (I forget the correct LVM terminology, I believe it's logical volumes). There are many howto's out there on setting up LVM and explaining what it does, I would suggest having a look at that. Yep. But that means that the OP would have to backup and restore. Alexander Skwar -- He is the MELBA-BEING ... the ANGEL CAKE ... XEROX him ... XEROX him -- -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
Alexander Skwar wrote: Shawn Haggett wrote: LVM would indeed be a solution. Instead of creating many disk partitions, you would simply create one large one the size of the disk. Yes, you could. But if you go that way, you don't have to create any partitions at all. Instead, you can also use /dev/hda with LVM. There are some limitations concerning lvm. I remember it is not recommended to use it for swap, root and /boot (and probably some more)... Jarry -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
On Sunday 12 February 2006 06:45, Jarry [EMAIL PROTECTED] wrote about 'Re: [gentoo-user] Max Number of Partitions': Alexander Skwar wrote: Shawn Haggett wrote: LVM would indeed be a solution. Instead of creating many disk partitions, you would simply create one large one the size of the disk. Yes, you could. But if you go that way, you don't have to create any partitions at all. Instead, you can also use /dev/hda with LVM. There are some limitations concerning lvm. I remember it is not recommended to use it for swap, root and /boot (and probably some more)... Some distros (kubuntu, I believe) use LVM swap by default if you use LVM. While this could theoretically cause a problem, I'm fairly sure that any problem encountered would be an acceptable lvm2 or device-mapper bug. Putting swap on LVM does have the distinct advantage of allowing swap to be resized when you add or remove (!) ram -- I like swap to be ~2x ram. I do not run LVM on swap, but that's because my swap is a resizable hw raid 0 volume that I wouldn't want to store other data on. (Data goes on raid 5 or 6.) It's not possible without some trickery to run /boot on LVM, since grub doesn't understand lvm and won't be able to find your files. Lilo may make this possible, but I keep my /boot off of LVM because I prefer grub and it feels right to make boot a real partition. Root on LVM is entirely possible. I've run that way since I initially installed linux (well, initially, this time around). You do have to create either an initrd or an initramfs that loads any needed modules that are not built in and activates the lvm logical volumes; genkernel can do this for you on gentoo. Other distros also provide tools to do the same thing, I recommend placing root on LVM for the same reasons any mount point goes on LVM: dynamic growing and shrinking of the filesystem. Ext2/3, JFS, XFS, and ReiserFS all support growing a filesystem without unmounting it, I believe (I only use reiserfs). [Shrinking a filesystem is another box of rocks, but I've done it successfully may a time.] If you only have a single hard disk my recommended layout is: /hda /hda1 -- /boot as big as you need it. I use 1G, but that's overkill for most people. /hda2 -- extended partition container /hda5 -- space remaining after /boot and swap as a single LVM physical volume /hda6 -- swap; 2x RAM You can than create a volume group with your single physical volume and begin cutting logical volumes out of it. The default limit to the number of logical volumes in a volume group is 255. When you need more storage you can add another hard drive, create a physical volume out of the whole drive (no need to partition), extend your volume group, and start growing your logical volumes across the new drive -- with no downtime if the drave can be hot plugged. -- Boyd Stephen Smith Jr. [EMAIL PROTECTED] ICQ: 514984 YM/AIM: DaTwinkDaddy -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
Jarry wrote: Alexander Skwar wrote: Shawn Haggett wrote: LVM would indeed be a solution. Instead of creating many disk partitions, you would simply create one large one the size of the disk. Yes, you could. But if you go that way, you don't have to create any partitions at all. Instead, you can also use /dev/hda with LVM. There are some limitations concerning lvm. I remember it is not recommended to use it for swap, Is that so? Why? Because of the risk of fragmentation? root and /boot I agree. But with a cleverly crafted initrd (ramdisk), / can easily be put in a LVM. (and probably some more)... No. But all that is not a contradiction to what I wrote :) Shawn wrote, that you could create only *ONE* partition on the disk and use it for LVM. I replied and said, that in this case, it might make some sense to skip the partitioning alltogether and use the complete disk (ie. without partitions) for LVM. Alexander Skwar -- slashdot my US geograpy is lousy...lol knghtbrd so's mine and I live here lol -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
Boyd Stephen Smith Jr. wrote: On Sunday 12 February 2006 06:45, Jarry [EMAIL PROTECTED] wrote about 'Re: [gentoo-user] Max Number of Partitions': Alexander Skwar wrote: Shawn Haggett wrote: LVM would indeed be a solution. Instead of creating many disk partitions, you would simply create one large one the size of the disk. Yes, you could. But if you go that way, you don't have to create any partitions at all. Instead, you can also use /dev/hda with LVM. There are some limitations concerning lvm. I remember it is not recommended to use it for swap, root and /boot (and probably some more)... Some distros (kubuntu, I believe) use LVM swap by default if you use LVM. While this could theoretically cause a problem, Could it? How and why? I'm fairly sure that any problem encountered would be an acceptable lvm2 or device-mapper bug. Ah, I see, that's what you mean. You're right. Putting swap on LVM does have the distinct advantage of allowing swap to be resized when you add or remove (!) ram -- I like swap to be ~2x ram. Well, it's very easy to create a swap file. As that's no longer a disadvantage performancewise, what you stated is not an argument for LVM. Actually, because of the fragmentation, I'd understand if people wouldn't want to resize the swap LV. Instead, I'd create another swap LV. Root on LVM is entirely possible. I've run that way since I initially installed linux (well, initially, this time around). You do have to create either an initrd or an initramfs that loads any needed modules that are not built in and activates the lvm logical volumes; genkernel can do this for you on gentoo. That's right. But if you also wish to use suspend-to-disk (swsusp or http://suspend2.net/ ; suspend2-sources), you won't be able to use a genkernel created initrd. Other distros also provide tools to do the same thing, I recommend placing root on LVM for the same reasons any mount point goes on LVM: dynamic growing and shrinking of the filesystem. Ext2/3, JFS, XFS, and ReiserFS all support growing a filesystem without unmounting it, I believe (I only use reiserfs). [Shrinking a filesystem is another box of rocks, but I've done it successfully may a time.] If you only have a single hard disk my recommended layout is: /hda /hda1 -- /boot as big as you need it. I use 1G, but that's overkill for most people. That's gross overkill :) I do very fine with only ~64 MB. /hda2 -- extended partition container /hda5 -- space remaining after /boot and swap as a single LVM physical volume /hda6 -- swap; 2x RAM Very much like my layout :) You can than create a volume group with your single physical volume and begin cutting logical volumes out of it. The default limit to the number of logical volumes in a volume group is 255. When you need more storage you can add another hard drive, create a physical volume out of the whole drive (no need to partition), extend your volume group, and start growing your logical volumes across the new drive I'd *STRONGLY* urge to *NOT* do this, if we're talking about normal consumer hard disks and especially if no backups are done. What happens, if disk1 in a 2 disk VG goes broke? Nah, too dangerous for me. I use multiple Volume Groups. -- with no downtime if the drave can be hot plugged. True. Alexander Skwar -- Those of us who believe in the right of any human being to belong to whatever church he sees fit, and to worship God in his own way, cannot be accused of prejudice when we do not want to see public education connected with religious control of the schools, which are paid for by taxpayers' money. - Eleanor Roosevelt -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
On Sunday 12 February 2006 16:12, Boyd Stephen Smith Jr. wrote: /hda1 -- /boot as big as you need it. I use 1G, but that's overkill for most people. Can't help being curious - how much of that space do you actually use?? I currently use 48 MB on /boot. -- Bo Andresen -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
On 2/12/06, Boyd Stephen Smith Jr. [EMAIL PROTECTED] wrote: I'm thinking of some obsure case where the code or data needed to read swap has been swapped out. BTW, I have been using swap on LVM (on an encrypted PV) for quite some time, without any trouble, including using suspend-to-ram and suspend-to-disk. If there were an obscure case, I think that would be it. I am pretty sure the kernel locks the device-mapper code into memory, so that it can never be swapped out. -Richard -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Francesco Riosa wrote: Mick wrote: Hi All, I think that I have run out of partitions: http://publib.boulder.ibm.com/infocenter/dsichelp/ds6000ic/index.jsp?topic=/com.ibm.storage.smric.help.doc/f2c_linuxscsilimit_2hsag9.html Although I have created up to 17 partitions on a SATA, I cannot mount them. :-( Before I start consolidating OS and data partitions to keep the number below 15, is there an alternative to this? Not that I know, sata disk are managed like scsi ones limiting the number of partitions to 1-15 . Someone, somewhere, one time told me that lvm could address that in some manner but I've never seen how. LVM would indeed be a solution. Instead of creating many disk partitions, you would simply create one large one the size of the disk. Then using LVM create as many virtual partitions as you need (I forget the correct LVM terminology, I believe it's logical volumes). There are many howto's out there on setting up LVM and explaining what it does, I would suggest having a look at that. -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.2 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFD7ZynQv6DFiTKHhkRAiwoAJ98PVJprssDCFsrSnum+QGtlhOslgCffC8p FeOULJkkA8MdhB17E8kI8X8= =M7NT -END PGP SIGNATURE- -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Max Number of Partitions
Mick wrote: Hi All, I think that I have run out of partitions: http://publib.boulder.ibm.com/infocenter/dsichelp/ds6000ic/index.jsp?topic=/com.ibm.storage.smric.help.doc/f2c_linuxscsilimit_2hsag9.html Although I have created up to 17 partitions on a SATA, I cannot mount them. :-( Before I start consolidating OS and data partitions to keep the number below 15, is there an alternative to this? Not that I know, sata disk are managed like scsi ones limiting the number of partitions to 1-15 . Someone, somewhere, one time told me that lvm could address that in some manner but I've never seen how. -- gentoo-user@gentoo.org mailing list
