Re: [CentOS] Newer versoin of tar 1.26 on Centos 7
Hello Klaus, On Wed, 16 Sep 2020 13:13:57 +0200 Klaus Kolle wrote: > Is it possible to find a repository that hold a newer version of tar. > The current version is 1.26 > > I have some students trying to build Yocto project on my Centos 7 host, > but OpenEmbedded reports incompatibility problems with the current > version of tar. > > I thank you on beforehand for any help. On the other side, building tar from the (latest) sources is quite easy. That's what I'd do. Regards, -- wwp https://useplaintext.email/ pgpXbB4HgsSyl.pgp Description: OpenPGP digital signature ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] storage for mailserver
On 16/09/2020 17:11, Michael Schumacher wrote: hi, I am planning to replace my old CentOS 6 mail server soon. Most details are quite obvious and do not need to be changed, but the old system was running on spinning discs and this is certainly not the best option for todays mail servers. With spinning discs, HW-RAID6 was the way to go to increase reliability and speed. Today, I get the feeling, that traditional RAID is not the best option for SSDs. I am reading that all RAID members in SSD-arrays age synchronously so that the risk of a massive failure of more than one disk is more likely than with HDDs. There are many other concerns like excessive write load compared to non-raid systems, etc. Is there any common sense what disk layout should be used these days? I have been looking for some kind of master-slave system, where the (one or many) SSD is taking all writes and reads, but the slave HDD runs in parallel as a backup system like in a RAID1 system. Is there any such system? Any thoughts? You can achieve this with a hybrid RAID1 by mixing SSDs and HDDs, and marking the HDD members as --write-mostly, meaning most of the reads will come from the faster SSDs retaining much of the speed advantage, but you have the redundancy of both SSDs and HDDs in the array. Read performance is not far off native write performance of the SSD, and writes mostly cached / happen in the background so are not so noticeable on a mail server anyway. I kind of stumbled across this setup by accident when I added an NVMe SSD to an existing RIAD1 array consisting of 2 HDDs. # cat /proc/mdstat Personalities : [raid1] md127 : active raid1 sda1[2](W) sdb1[4](W) nvme0n1p1[3] 485495616 blocks super 1.0 [3/3] [UUU] bitmap: 3/4 pages [12KB], 65536KB chunk See how we have 3 devices in the above RAID1 array, 2 x HDDs, marked with a (W) indicating they are in --write-mostly mode, and one SSD (MVMe) device. I just went for 3 devices in the array as it started life as a 2 x HDD array and I added the third SSD device, but you can mix and match to suit your needs. See the following article which may be helpful or search 'mdadm write-mostly' for more info. https://www.tansi.org/hybrid/ ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] storage for mailserver
On 2020-09-16 11:26, Stephen John Smoogen wrote: On Wed, 16 Sep 2020 at 12:12, Michael Schumacher < michael.schumac...@pamas.de> wrote: hi, I am planning to replace my old CentOS 6 mail server soon. Most details are quite obvious and do not need to be changed, but the old system was running on spinning discs and this is certainly not the best option for todays mail servers. With spinning discs, HW-RAID6 was the way to go to increase reliability and speed. Today, I get the feeling, that traditional RAID is not the best option for SSDs. I am reading that all RAID members in SSD-arrays age synchronously so that the risk of a massive failure of more than one disk is more likely than with HDDs. There are many other concerns like excessive write load compared to non-raid systems, etc. Is there any common sense what disk layout should be used these days? I have been looking for some kind of master-slave system, where the (one or many) SSD is taking all writes and reads, but the slave HDD runs in parallel as a backup system like in a RAID1 system. Is there any such system? I don't think so because the drives would always be out of sync but in a restart it would be hard to know if the drive is out of sync for a good reason or a bad one. For most of the SSD raids, I have seen people just making sure to buy disks which are spec'd for more writes or similar 'smarter' enterprise trim. I have also read about the synchronicity problem but I think this may be a theory vs reality problem. In theory they should all fail at once, in reality at least for the arrays I have used for 3 years, they seem to fail in different times. that said, I only have 3 systems over 3 years with SSD drives running RAID6 so I only have anecdata versus data. I fully agree about synchronous failure of SSDs in RAID to be made up or grossly overrated. SSD failure _probablity_ is increased with number of write operations (into the same area). Failure still has stochastic nature. If SSD is spec'ed for N number of writes, it doesn't mean on the write N+1 SSD will fail. It only means that after N number of writes failure probability is below [some acceptable value], which, however is much higher of that of unused SSD. That said, single SSD failure probability after long run is some small value, say q. Event of failure of another SSD is independent event from failure of first failed SSD (even though their probabilities q both increase with number of writes) hence probability of failures are: one SSD failed: q two SSDs failed: (q)^2 three SSDs failed: (q)^3 thus multi-failures (say, within some period of time, say 1 day, or 1 week) still are way less probable events than single failure. The following numbers have nothing to do with probability of failure of some devices, it is just an illustration, so: if q = 10 ^ (-10) (ten to the minus 10th power), then (q)^2 = 10 ^ (-20) (q)^3 = 10 ^ (-30) My apologies for saying trivial things, they just give IMHO a feeling of what to take into consideration, and what to ignore safely. And no, I don't intend to start flame war on views of statistics, or on hardware vs software RAIDs, or RAIDs vs zfs. Just think it over and draw your own conclusions. Valeri Any thoughts? best regards Michael Schumacher ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos -- Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] storage for mailserver
Hi Michael, RAID 1 is not uncommon with SSDs (be them SATA/SAS/NVMe). RAID 5/6 wear SSD drives more so are generally best avoided. You really need to monitor your SSDs health to help avoid failures. And obviously always have your backups... -yoctozepto On Wed, Sep 16, 2020 at 6:12 PM Michael Schumacher wrote: > > hi, > > I am planning to replace my old CentOS 6 mail server soon. Most details > are quite obvious and do not need to be changed, but the old system > was running on spinning discs and this is certainly not the best > option for todays mail servers. > > With spinning discs, HW-RAID6 was the way to go to increase reliability > and speed. > Today, I get the feeling, that traditional RAID is not the best > option for SSDs. I am reading that all RAID members in SSD-arrays age > synchronously so that the risk of a massive failure of more than one > disk is more likely than with HDDs. There are many other concerns like > excessive write load compared to non-raid systems, etc. > > Is there any common sense what disk layout should be used these days? > > I have been looking for some kind of master-slave system, where the > (one or many) SSD is taking all writes and reads, but the slave HDD > runs in parallel as a backup system like in a RAID1 system. Is there > any such system? > > Any thoughts? > > best regards > Michael Schumacher > > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] storage for mailserver
Hi Michael, With SSD's, no matter what storage technology is used, you pay your money and you take your choice. The more expensive SSD's have higher I/O rates, higher data bandwidth and better durability. I would go for NVMe as this gives a higher data rate with PCIe 3.0 and PCIe 4.0 (twice the data rate) ones are just coming in to the market. I believe that traditional Raid 5 and 6 are not required for SSD's I have configured all my customer SSD subsystems for Raid 1 (mirror), reduced overhead. Cost defines if the above is acceptable. Also, do you use hardware or software Raid 1. There are many other questions but the above is a start. Regards, Mark Woolfson MW Consultancy Ltd Leeds LS18 4LY United Kingdom Tel: +44 113 259 1204 Mob: +44 786 065 2778 -Original Message- From: Michael Schumacher Sent: Wednesday, September 16, 2020 5:11 PM To: CentOS mailing list Subject: [CentOS] storage for mailserver hi, I am planning to replace my old CentOS 6 mail server soon. Most details are quite obvious and do not need to be changed, but the old system was running on spinning discs and this is certainly not the best option for todays mail servers. With spinning discs, HW-RAID6 was the way to go to increase reliability and speed. Today, I get the feeling, that traditional RAID is not the best option for SSDs. I am reading that all RAID members in SSD-arrays age synchronously so that the risk of a massive failure of more than one disk is more likely than with HDDs. There are many other concerns like excessive write load compared to non-raid systems, etc. Is there any common sense what disk layout should be used these days? I have been looking for some kind of master-slave system, where the (one or many) SSD is taking all writes and reads, but the slave HDD runs in parallel as a backup system like in a RAID1 system. Is there any such system? Any thoughts? best regards Michael Schumacher ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] storage for mailserver
On Wed, 16 Sep 2020 at 12:12, Michael Schumacher < michael.schumac...@pamas.de> wrote: > hi, > > I am planning to replace my old CentOS 6 mail server soon. Most details > are quite obvious and do not need to be changed, but the old system > was running on spinning discs and this is certainly not the best > option for todays mail servers. > > With spinning discs, HW-RAID6 was the way to go to increase reliability > and speed. > Today, I get the feeling, that traditional RAID is not the best > option for SSDs. I am reading that all RAID members in SSD-arrays age > synchronously so that the risk of a massive failure of more than one > disk is more likely than with HDDs. There are many other concerns like > excessive write load compared to non-raid systems, etc. > > Is there any common sense what disk layout should be used these days? > > I have been looking for some kind of master-slave system, where the > (one or many) SSD is taking all writes and reads, but the slave HDD > runs in parallel as a backup system like in a RAID1 system. Is there > any such system? > > I don't think so because the drives would always be out of sync but in a restart it would be hard to know if the drive is out of sync for a good reason or a bad one. For most of the SSD raids, I have seen people just making sure to buy disks which are spec'd for more writes or similar 'smarter' enterprise trim. I have also read about the synchronicity problem but I think this may be a theory vs reality problem. In theory they should all fail at once, in reality at least for the arrays I have used for 3 years, they seem to fail in different times. that said, I only have 3 systems over 3 years with SSD drives running RAID6 so I only have anecdata versus data. > Any thoughts? > > best regards > Michael Schumacher > > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos > -- Stephen J Smoogen. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
[CentOS] storage for mailserver
hi, I am planning to replace my old CentOS 6 mail server soon. Most details are quite obvious and do not need to be changed, but the old system was running on spinning discs and this is certainly not the best option for todays mail servers. With spinning discs, HW-RAID6 was the way to go to increase reliability and speed. Today, I get the feeling, that traditional RAID is not the best option for SSDs. I am reading that all RAID members in SSD-arrays age synchronously so that the risk of a massive failure of more than one disk is more likely than with HDDs. There are many other concerns like excessive write load compared to non-raid systems, etc. Is there any common sense what disk layout should be used these days? I have been looking for some kind of master-slave system, where the (one or many) SSD is taking all writes and reads, but the slave HDD runs in parallel as a backup system like in a RAID1 system. Is there any such system? Any thoughts? best regards Michael Schumacher ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] how to restore deleted directory/files
On 2020-09-16 06:21, qw wrote: Hi, I remove one directory by running rm -fr ./some-dir. How to restore the directory and its files in the directory? 1. restore from latest backup. 2. if you are very facile with Linux, then you culd try a. remount read only the mount point where removed directory/file lives (every write may obliterate some of removed stuff) - AS SOON AS POSSIBLE b. make dd copy of the whole partition (underlying device actually) to file, make another copy of that, and use filesystem debugging tools to undo what your "rm -rf ..." did on that copy. But this option is for experts in the field, which judging from your question you are not, so go to 1. Or go to 3. 3. send drive to one of commercial recovery companies. They charge a lot ($1000 will be good of least expensive ones, who charge much less are likely just frauds), the real ones, as they will try to do what is in 2. If you need advise on recovery companies, I can give some, though my own plan always is: I have a good backup. Valeri Thanks! Regards Andrew ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos -- Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] how to restore deleted directory/files
On Wed, Sep 16, 2020 at 10:00:05PM +0800, qw wrote: > > Thanks for your advice. I will try the tools. > > > I also found the article about how to create and mount image. > > https://midnightprogrammer.net/post/create-mount-and-unmount-img-files-in-ubuntu/ > > > The article says, the image file created by dd should formated in > ubuntu. > > > For Centos, should I format the image file before mounting it as > virtual read-only disk? You generally don't want to mount it at all, it won't help you recover anything. The article is for creating a fresh, unformatted disk image and mounting it via the loopback. Since this image is already formatted, you'd just be deleting data by formatting it. Anyway, you don't generally need to mount anything if you're using photorec or similar tools. -- Jonathan Billings ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] how to restore deleted directory/files
Hi, >> >> Thanks for your reply. The file system type is xfs. And I found >> xfsdump/xfsrestore can undo the remove. > >Hm, are you sure you can use xfsdump/xfsrestore for this? > xfsdump/xfsrestore can't do the recovery. >> I use dd to copy the partition as one image file. How do I mount the image >> as read-only device? Then I can try to recover the deleted files/directory >> anytime. > >Mount the image with the option '-o ro' as read-only. > >Depending on the kind of data you removed you could use 'testdisk' or >'photorec' to recover. Make sure to only use a copied image to test. Thanks for your advice. I will try the tools. I also found the article about how to create and mount image. https://midnightprogrammer.net/post/create-mount-and-unmount-img-files-in-ubuntu/ The article says, the image file created by dd should formated in ubuntu. For Centos, should I format the image file before mounting it as virtual read-only disk? Thanks! Regards andrew At 2020-09-16 21:32:49, "Simon Matter" wrote: >> Hi, >> >> >> Thanks for your reply. The file system type is xfs. And I found >> xfsdump/xfsrestore can undo the remove. > >Hm, are you sure you can use xfsdump/xfsrestore for this? > >> >> >> I use dd to copy the partition as one image file. How do I mount the image >> as read-only device? Then I can try to recover the deleted files/directory >> anytime. > >Mount the image with the option '-o ro' as read-only. > >Depending on the kind of data you removed you could use 'testdisk' or >'photorec' to recover. Make sure to only use a copied image to test. > >Regards, >Simon > >___ >CentOS mailing list >CentOS@centos.org >https://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] how to restore deleted directory/files
> Hi, > > > Thanks for your reply. The file system type is xfs. And I found > xfsdump/xfsrestore can undo the remove. Hm, are you sure you can use xfsdump/xfsrestore for this? > > > I use dd to copy the partition as one image file. How do I mount the image > as read-only device? Then I can try to recover the deleted files/directory > anytime. Mount the image with the option '-o ro' as read-only. Depending on the kind of data you removed you could use 'testdisk' or 'photorec' to recover. Make sure to only use a copied image to test. Regards, Simon ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Newer versoin of tar 1.26 on Centos 7
Hi James On 16.09.2020 14.13, James Pearson wrote: > I have no idea what 'Yocto' is, but CentOS 7 includes two other tar > utilities: 'bsdtar' and 'star' Yocto is for building custom Linux distributions. It builds on OpenEmbedded. > > Maybe one of those will give you what you need? I'll give it at try. > > James Pearson Thanks for your reply. |< -- Med venlig hilsen Klaus Kolle Teknikumingeniør, B.Sc.EE., e-mail: kl...@kolle.dk Master of ITwww : www.kolle.dk Asger Jorns Vej 17 Telephone : +4522216044 DK-8600 Silkeborg, Denmark "Man skal ikke tilskrive til sammensværgelser hvad der tilstrækkeligt kan forklares af inkompetence" Poul Henning Kamp Planlægning er tanker om noget man agter at gøre en gang i fremtiden, hvis omstændighederne tillader det. Klaus Kolle 2006 Perfection is achieved not when nothing more to add, but when there is nothing more left to take away. Antoine de Saint-Exupery signature.asc Description: OpenPGP digital signature ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] how to restore deleted directory/files
Hi, Thanks for your reply. The file system type is xfs. And I found xfsdump/xfsrestore can undo the remove. I use dd to copy the partition as one image file. How do I mount the image as read-only device? Then I can try to recover the deleted files/directory anytime. Thanks! Regards Andrew At 2020-09-16 20:36:44, "Jonathan Billings" wrote: >On Wed, Sep 16, 2020 at 07:21:08PM +0800, qw wrote: >> I remove one directory by running rm -fr ./some-dir. How to restore >> the directory and its files in the directory? > >If you don't have backups, then you're pretty much out of luck. Don't >forget to back up any data that is important, and test your backups >regularly! > >Depending on the filesystem, there might be ways to recover it, but >the first thing you need to do is stop using the disk the files were >on. Power it off. There are some tools that you can use to recover >it, but it's not 100% effective. > >If it's very important and you are willing to spend money, there are >data recovery services that might be able to extract the data. > >-- >Jonathan Billings >___ >CentOS mailing list >CentOS@centos.org >https://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] how to restore deleted directory/files
On Wed, Sep 16, 2020 at 07:21:08PM +0800, qw wrote: > I remove one directory by running rm -fr ./some-dir. How to restore > the directory and its files in the directory? If you don't have backups, then you're pretty much out of luck. Don't forget to back up any data that is important, and test your backups regularly! Depending on the filesystem, there might be ways to recover it, but the first thing you need to do is stop using the disk the files were on. Power it off. There are some tools that you can use to recover it, but it's not 100% effective. If it's very important and you are willing to spend money, there are data recovery services that might be able to extract the data. -- Jonathan Billings ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Newer versoin of tar 1.26 on Centos 7
I have no idea what 'Yocto' is, but CentOS 7 includes two other tar utilities: 'bsdtar' and 'star' Maybe one of those will give you what you need? James Pearson From: CentOS on behalf of Klaus Kolle Sent: 16 September 2020 12:13 To: centos@centos.org Subject: [CentOS] Newer versoin of tar 1.26 on Centos 7 Is it possible to find a repository that hold a newer version of tar. The current version is 1.26 I have some students trying to build Yocto project on my Centos 7 host, but OpenEmbedded reports incompatibility problems with the current version of tar. I thank you on beforehand for any help. |< -- Med venlig hilsen Klaus Kolle Teknikumingeniør, B.Sc.EE., e-mail: kl...@kolle.dk Master of ITwww : www.kolle.dk Asger Jorns Vej 17 Telephone : +4522216044 DK-8600 Silkeborg, Denmark "Man skal ikke tilskrive til sammensværgelser hvad der tilstrækkeligt kan forklares af inkompetence" Poul Henning Kamp Planlægning er tanker om noget man agter at gøre en gang i fremtiden, hvis omstændighederne tillader det. Klaus Kolle 2006 Perfection is achieved not when nothing more to add, but when there is nothing more left to take away. Antoine de Saint-Exupery ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
[CentOS] how to restore deleted directory/files
Hi, I remove one directory by running rm -fr ./some-dir. How to restore the directory and its files in the directory? Thanks! Regards Andrew ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
[CentOS] Newer versoin of tar 1.26 on Centos 7
Is it possible to find a repository that hold a newer version of tar. The current version is 1.26 I have some students trying to build Yocto project on my Centos 7 host, but OpenEmbedded reports incompatibility problems with the current version of tar. I thank you on beforehand for any help. |< -- Med venlig hilsen Klaus Kolle Teknikumingeniør, B.Sc.EE., e-mail: kl...@kolle.dk Master of ITwww : www.kolle.dk Asger Jorns Vej 17 Telephone : +4522216044 DK-8600 Silkeborg, Denmark "Man skal ikke tilskrive til sammensværgelser hvad der tilstrækkeligt kan forklares af inkompetence" Poul Henning Kamp Planlægning er tanker om noget man agter at gøre en gang i fremtiden, hvis omstændighederne tillader det. Klaus Kolle 2006 Perfection is achieved not when nothing more to add, but when there is nothing more left to take away. Antoine de Saint-Exupery signature.asc Description: OpenPGP digital signature ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
