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Prevent kernel upgrade unless given dependencies satisfied
by Ross S. W. Walker 06 Dec '07

06 Dec '07

Dear List Members, Is there a way to prevent a kernel from being upgraded unless a list of given dependencies are satisfied? What I am getting at is sometimes updated kernels are available before the upgraded versions of the kernel modules in 'extras' are (ie drbd). If there were a way to list these modules as dependencies that must be satisfied before a kernel upgrade can be performed it would prevent a lot of pain around upgrade management. Thanks, Ross S. W. Walker Information Systems Manager Medallion Financial, Corp. 437 Madison Avenue 38th Floor New York, NY 10022 Tel: (212) 328-2165 Fax: (212) 328-2125 WWW: http://www.medallion.com <http://www.medallion.com/> ______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.

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Re: [CentOS] Filesystem that doesn't store duplicate data
by Ross S. W. Walker 06 Dec '07

06 Dec '07

These are all good and valid issues. Thinking about it some more I might just implement it as a system service that scans given disk volumes in the background, keeps a hidden directory where it stores it's state information and hardlinks named after the md5 hash of the files on the volume. If a collission occurs with an existing md5 hash then the new file is unlinked and re-linked to the md5 hash file, if an md5 hash file exists with no secondary links then it is removed. Maybe monitor the journal or use inotify to just get new files and once a week do a full volume scan. This way the file system performs as well as it normally does and as things go forward duplicate files are eliminated (combined). Of course the problem arises of what to do when 1 duplicate is modified, but the other should remain the same... Of course what you said about revisions that differ just a little won't take advantage of this, but it's file level so it only works with whole files, still better then nothing. -Ross -----Original Message----- From: centos-bounces(a)centos.org <centos-bounces(a)centos.org> To: CentOS mailing list <centos(a)centos.org> Sent: Thu Dec 06 08:10:38 2007 Subject: Re: [CentOS] Filesystem that doesn't store duplicate data On Thursday 06 December 2007, Ross S. W. Walker wrote: > How about a FUSE file system (userland, ie NTFS 3G) that layers > on top of any file system that supports hard links That would be easy but I can see a few issues with that approach: 1) On file level rather than block level you're going to be much more inefficient. I for one have gigabytes of revisions of files that have changed a little between each file. 2) You have to write all datablocks to disk and then erase them again if you find a match. That will slow you down and create some weird behavior. I.e. you know the FS shouldn't store duplicate data, yet you can't use cp to copy a 10G file if only 9G are free. If you copy a 8G file, you see the usage increase till only 1G is free, then when your app closes the file, you are going to go back to 9G free... 3) Rather than continuously looking for matches on block level, you have to search for matches on files that can be any size. That is fine if you have a 100K file - but if you have a 100M or larger file, the checksum calculations will take you forever. This means rather than adding a specific, small penalty to every write call, you add a unknown penalty, proportional to file size when closing the file. Also, the fact that most C coders don't check the return code of close doesn't make me happy there... Peter. _______________________________________________ CentOS mailing list CentOS(a)centos.org http://lists.centos.org/mailman/listinfo/centos ______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.

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File system cache corruption with CentOS4?
by James Pearson 06 Dec '07

06 Dec '07

Just wondering if anyone else has come across an issue where files cached in memory appear to become 'corrupted' - for example, on one workstation, I've just had the issue: # yum Traceback (most recent call last): File "/usr/bin/yum", line 4, in ? import yum File "__init__.py", line 36, in ? File "config.py", line 34, in ? File "repos.py", line 29, in ? File "repoMDObject.py", line 18, in ? strace'ing the process didn't show up anything obvious However, I ran a simple process that just grabs memory - which has the side effect of 'flushing' caches from memory. After, doing this, yum ran fine ... I've seen this issue quite a few times with various applications and on different machines - and flushing the caches in the way fixes the issue ... OK, it could be a real memory problem, but given the number of times I see this issue, on machines that are fine otherwise, it makes we wonder if it could be a cache issue ... All the machines are running a CentOS4.4 based kernel - (I plan to move to a CentOS4.6 based kernel when it is out). The kernel is not a vanilla CentOS4.4 kernel - it includes a few small non-standard patches - but nothing that touches the VFS layer (AFAIK). The issue occurs on i686 or x86_64 boxes. All machines have at least 4GB of memory. They also use the nVidia binary-only module. Anyone seen issues like this? Thanks James Pearson

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smartd.conf get overridden
by Christian Volker 06 Dec '07

06 Dec '07

Yohoo! I have some issues with the smartd in CentOS5/x64 I edited the /etc/smartd.conf for my needs and restarted the smartd with "service smartd restart". But the start script is overriding my file. I checked it and saw the following lines: ---------------/etc/init.d/smartd------------ case "$1" in start | reload | restart) GEN_CONF="*SMARTD*AUTOGENERATED*" [ ! -f /etc/smartd.conf ] || read DUMMY GEN_CONF DUMMY </etc/smartd.conf \ && [ "$GEN_CONF" == "*SMARTD*AUTOGENERATED*" ] \ && smartd-conf.py 2>/dev/null >/etc/smartd.conf.new-autogenerated \ && mv -f /etc/smartd.conf.new-autogenerated /etc/smartd.conf ;; esac ---------------/etc/init.d/smartd------------ So how can I prevent my file beeeing overriden without editing this script (which will probably get lots the next update)? ------/etc/sysctl/smartmontools--------- # command line options for smartd smartd_opts="-q never" ---------------------------------------- Any ideas? Christian Volker Technical Support Engineer -- Parnell House, Barrack Square, Ballincollig, Co. Cork, Ireland t: + 353 21 466 0019 e: cvolker(a)vmware.com

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Filesystem that doesn't store duplicate data
by rsivak＠istandfor.com 06 Dec '07

06 Dec '07

Is there such a filesystem available? It seems like it wouldn't be too hard to implement... Basically do things on a block by block basis. Store md5 of a block in the table, and when writing a new block, check if the md5 already exists and then point the new block to the old block. Since md5 is not guaranteed unique, might need to do a diff between the 2 blocks and if the blocks are indeed different, handle it somehow. When modifying an existing block that has multiple pointers, copy the block and modify the new block. I know I'm oversimplifying things a lot, but something like this could work, no? Would be a great filesystem to store backups on, or things like vmware volumes... Russ Sent from my Verizon Wireless BlackBerry

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MP3 encoding with Sound-Juicer
by Olaf Mueller 06 Dec '07

06 Dec '07

Hello, what do I need to encode mp3 with Sound Juicer under CentOS 5.1? Thank you Olaf

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LVM2: large volume problem?
by Antonio da Silva Martins Junior 06 Dec '07

06 Dec '07

Hi all, I'm having problems to create/resize an lv up to 1T (well I can't reach 300G), my system is a CentOS 5.1 x86_64 on a Dell 2950 with 6x500G SATA (RAID5 to aprox. 2.5T) [root@Mugello ~]# fdisk -l Disk /dev/sda: 2497.7 GB, 2497791918080 bytes 255 heads, 63 sectors/track, 303672 cylinders Units = cilindros of 16065 * 512 = 8225280 bytes Dispositivo Boot Start End Blocks Id System /dev/sda1 * 1 13 104391 83 Linux /dev/sda2 14 36323 291657269+ 8e Linux LVM [root@Mugello ~]# vgdisplay --- Volume group --- VG Name sys System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 26 VG Access read/write VG Status resizable MAX LV 0 Cur LV 4 Open LV 4 Max PV 0 Cur PV 1 Act PV 1 VG Size 2,27 TB PE Size 32,00 MB Total PE 74436 Alloc PE / Size 512 / 16,00 GB Free PE / Size 73924 / 2,26 TB VG UUID yuxYGR-dLVP-DuXz-i4oP-14ep-aYWQ-xBp6f1 [root@Mugello ~]# lvs LV VG Attr LSize Origin Snap% Move Log Copy% root sys -wi-ao 4,00G swap sys -wi-ao 2,00G usr sys -wi-ao 5,00G var sys -wi-ao 5,00G When I try to create a 1T lv it gives me this error: [root@Mugello ~]# lvcreate -L1T -nstor sys device-mapper: reload ioctl failed: Argumento inválido Failed to activate new LV. and on /var/log/messages I had this: Dec 6 08:31:27 Mugello kernel: device-mapper: table: device 8:2 too small for target Dec 6 08:31:27 Mugello kernel: device-mapper: table: 253:4: linear: dm-linear: Device lookup failed Dec 6 08:31:27 Mugello kernel: device-mapper: ioctl: error adding target to table the lv is created: [root@Mugello ~]# lvs LV VG Attr LSize Origin Snap% Move Log Copy% root sys -wi-ao 4,00G stor sys -wi-d- 1,00T swap sys -wi-ao 2,00G usr sys -wi-ao 5,00G var sys -wi-ao 5,00G but is unusable: [root@Mugello ~]# mkfs -t ext3 /dev/sys/stor mke2fs 1.39 (29-May-2006) Could not stat /dev/sys/stor --- Arquivo ou diretório não encontrado The device apparently does not exist; did you specify it correctly? [root@Mugello ~]# ls -la /dev/mapper/ total 0 drwxr-xr-x 2 root root 160 Dez 6 09:02 . drwxr-xr-x 12 root root 4220 Dez 6 07:43 .. crw------- 1 root root 10, 63 Dez 6 07:43 control brw-rw---- 1 root disk 253, 0 Dez 6 07:43 sys-root brw-rw---- 1 root disk 253, 4 Dez 6 09:02 sys-stor brw-rw---- 1 root disk 253, 3 Dez 6 07:43 sys-swap brw-rw---- 1 root disk 253, 1 Dez 6 07:43 sys-usr brw-rw---- 1 root disk 253, 2 Dez 6 07:43 sys-var [root@Mugello ~]# mkfs -t ext3 /dev/mapper/sys-stor mke2fs 1.39 (29-May-2006) mkfs.ext3: Device size reported to be zero. Invalid partition specified, or partition table wasn't reread after running fdisk, due to a modified partition being busy and in use. You may need to reboot to re-read your partition table. If I try with a small size (less than 300G) it works well: [root@Mugello ~]# lvcreate -L100G -nstor sys Logical volume "stor" created [root@Mugello ~]# lvs LV VG Attr LSize Origin Snap% Move Log Copy% root sys -wi-ao 4,00G stor sys -wi-a- 100,00G swap sys -wi-ao 2,00G usr sys -wi-ao 5,00G var sys -wi-ao 5,00G What can I try to do to create an lv with 1T?? Thanks in advance, Antonio. -- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Antonio S. Martins Jr. - Support Analist | "Only The Shadow Knows | | Universidade Estadual de Maringá - Brasil| what evil lurks in the | | NPD - Núcleo de Processamento de Dados | Heart of Men!" | | E-Mail: asmartins(a)uem.br / shadow(a)uem.br | !!! Linux User: 52392 !!! | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -- Esta mensagem foi verificada pelo sistema de antiv�rus e acredita-se estar livre de perigo.

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RE: [CentOS] Announcing the CentOS on Laptops initiative
by Trevor Benson 06 Dec '07

06 Dec '07

> Sadly, for now, you have to request access to be allowed to create or > edit > these pages. I hope in the future we will have a more liberal view wrt. > the wiki. > > PS I created this structure for your X60 for now, I plan to add my own > laptops soon (but it does not include a X60). If you can add your > information to this existing page, I am sure this is very valuable for > another X60 owner. Can I get a Thinkpad R51 page setup if not already and access. About to blow out the FC6 and load CentOS 5 since I have to finagle the wifi every so often. Figured document as I go lest I forget. Trevor

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Arp problems I think ...
by Alan Bunch 06 Dec '07

06 Dec '07

Please bear with me as I know I have included a lot of detail. Description Redhat AS 3 Kernel 2.4.21-47.0.1.ELsmp eth0 HWaddr 00:07:E9:11:30:76 inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0 eth0:1 HWaddr 00:07:E9:11:30:76 inet addr:192.168.3.1 Bcast:192.168.3.255 Mask:255.255.255.0 This interface is up but with no IP address eth1 HWaddr 00:07:E9:11:30:77 eth1.101 10.10.1.1 Bcast:10.10.1.255 Mask:255.255.255.0 vlan 101 eth1.102 10.10.2.1 Bcast:10.10.2.255 Mask:255.255.255.0 vlan 102 eth1.103 10.10.3.1 Bcast:10.10.3.255 Mask:255.255.255.0 vlan 103 eth1.104 10.10.4.1 Bcast:10.10.4.255 Mask:255.255.255.0 vlan 104 eth1.105 10.10.5.1 Bcast:10.10.5.255 Mask:255.255.255.0 vlan 105 eth1.106 10.10.6.1 Bcast:10.10.6.255 Mask:255.255.255.0 vlan 106 eth1.107 10.10.7.1 Bcast:10.10.7.255 Mask:255.255.255.0 vlan 107 eth1.108 10.10.8.1 Bcast:10.10.8.255 Mask:255.255.255.0 vlan 108 eth1.109 10.10.9.1 Bcast:10.10.9.255 Mask:255.255.255.0 vlan 109 eth2 Link encap:Ethernet HWaddr 00:06:5B:FE:56:C2 BROADCAST MULTICAST MTU:1500 Metric:1 eth3 Link encap:Ethernet HWaddr 00:06:5B:FE:56:C3 BROADCAST MULTICAST MTU:1500 Metric:1 This machine is routing between the vlans. When I ping 10.10.5.105 I get Host Unreachable. Here is tcpdump from the ping on the router. tcpdump -i eth1.105 14:10:28.254008 arp who-has 10.10.5.105 tell 10.10.5.1 14:10:29.250067 arp who-has 10.10.5.105 tell 10.10.5.1 14:10:30.250143 arp who-has 10.10.5.105 tell 10.10.5.1 Ok now I go to the device via a serial port and ping back to 10.10.5.1 ( the router ) and here is the tcpdump output tcpdump -i eth1.105 -n tcpdump: listening on eth1.105 14:12:06.706722 arp who-has 10.10.5.1 tell 10.10.5.105 14:12:06.706798 arp reply 10.10.5.1 is-at 0:7:e9:11:30:77 14:12:06.707715 10.10.5.105 > 10.10.5.1: icmp: echo request (DF) 14:12:06.707762 10.10.5.1 > 10.10.5.105: icmp: echo reply 14:12:07.723100 10.10.5.105 > 10.10.5.1: icmp: echo request (DF) 14:12:07.723136 10.10.5.1 > 10.10.5.105: icmp: echo reply Now of course I can ping 10.10.5.10 (the suspect device) from 10.10.5.1 ( the router ) ping 10.10.5.1 PING 10.10.5.1 (10.10.5.1) 56(84) bytes of data. 64 bytes from 10.10.5.1: icmp_seq=0 ttl=64 time=0.068 ms 64 bytes from 10.10.5.1: icmp_seq=1 ttl=64 time=0.039 ms This is fine untill the arp entry ages out. Then I back to not being able to ping the device. If I manually insert an arp table entry all is well. No filtering in the switches. Switches are SMC 6826 for the 10/100 and 8724 for the core and gig e. I have several similar symptoms like this in various places. I have some devices on vlans that I see the dhcp discover messages and I see the dhcp offer then the device sends another dhcp discover. This goes on for a few times and the device just waits and starts the process over. I feel that the problem lies in the handling of arp requests but I guess I just don't know enough about how linux handles them or how to control them to find a solution. Any ideas ? Alan

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Network performance
by Vitaly 06 Dec '07

06 Dec '07

I'm running RHEL/CentOS 3 (2.4.21-47.ELsmp) with Broadcom NIC and BASP bonding (bcm5700 v8.1.55) When network traffic is ~12MB/sec (== ~120K packets/sec) CPU system load is growing up to 50-60%%. Yes, I know, that small packets (~100 bytes/packet) are not optimal for network throughput, but in the short-middle term I cannot re-write our application. Are there any network driver / kernel parameters which can help me to increase network throughput? Replacing bcm5700 to tg3? Upgrading to RHEL 4 or 5 with kernel 2.6? Other ideas? Thanks, Vitaly

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