Re: email server - how to
On Wed, 30 Jun 2004 21:23, Dave Watkins <[EMAIL PROTECTED]> wrote: > Andreas John wrote: > >> Best to use 2U machines with the maximum number of disks IMHO. A 2U > >> machine should be able to have 5 disks. > > > > I say: 9 Disks without problems. e.g. pcicase > > http://www.pcicase.de/catalog/produktweb/IPC-C2-X/IPC-C2D.htm > > The question is with that many disks is a single raid 5 going to be > enough redundancy... Thats an awful lot of data to loose if 2 drives > fail. May be worth thinking about RAID6 or a couple of RAID5 arrays striped If you have two RAID-5 arrays striped then two disks can fail and lose all your data. If you have a 10 disk setup where one disk has already failed, and if all disks are equally likely to fail, then on a single RAID-5 any disk failure will lose your data while on a pair of striped RAID-5's the chance will be 4/9 that the next failure will lose the data. However in a RAID-5 when one disk has failed there is more work for the remaining disk, so it may be more likely that the RAID-5 which has already lost a disk will lose a second than having a disk die in a RAID-5 that's working fine. Another issue is that physical issues (vibration and temperature) can cause or trigger disk death. As a RAID-5 is likely to be comprised of disks that are near each other there may be a pattern to disk death. I would hope that RAID-6 would be significantly more reliable than RAID-5. However there are lots of other causes of data loss. If reads don't occur on all disks at the same time with checking of both parity blocks then a RAID-6 system will still fail if a disk returns bad data and claims it to be good. Performance will be better if you don't have to read all blocks in each stripe for every read, so I expect that most systems will support turning off the feature to read the entire stripe (and it may be the default for some). There are lots of physical issues that can take out multiple disks, anything that can take out two disks can probably take out three just as easily. These physical issues include repairmen who use a hammer as a CPU installation tool (this is not a joke). -- http://www.coker.com.au/selinux/ My NSA Security Enhanced Linux packages http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark http://www.coker.com.au/postal/Postal SMTP/POP benchmark http://www.coker.com.au/~russell/ My home page
Re: email server - how to
On Wed, 30 Jun 2004 21:23, Dave Watkins <[EMAIL PROTECTED]> wrote: > Andreas John wrote: > >> Best to use 2U machines with the maximum number of disks IMHO. A 2U > >> machine should be able to have 5 disks. > > > > I say: 9 Disks without problems. e.g. pcicase > > http://www.pcicase.de/catalog/produktweb/IPC-C2-X/IPC-C2D.htm > > The question is with that many disks is a single raid 5 going to be > enough redundancy... Thats an awful lot of data to loose if 2 drives > fail. May be worth thinking about RAID6 or a couple of RAID5 arrays striped If you have two RAID-5 arrays striped then two disks can fail and lose all your data. If you have a 10 disk setup where one disk has already failed, and if all disks are equally likely to fail, then on a single RAID-5 any disk failure will lose your data while on a pair of striped RAID-5's the chance will be 4/9 that the next failure will lose the data. However in a RAID-5 when one disk has failed there is more work for the remaining disk, so it may be more likely that the RAID-5 which has already lost a disk will lose a second than having a disk die in a RAID-5 that's working fine. Another issue is that physical issues (vibration and temperature) can cause or trigger disk death. As a RAID-5 is likely to be comprised of disks that are near each other there may be a pattern to disk death. I would hope that RAID-6 would be significantly more reliable than RAID-5. However there are lots of other causes of data loss. If reads don't occur on all disks at the same time with checking of both parity blocks then a RAID-6 system will still fail if a disk returns bad data and claims it to be good. Performance will be better if you don't have to read all blocks in each stripe for every read, so I expect that most systems will support turning off the feature to read the entire stripe (and it may be the default for some). There are lots of physical issues that can take out multiple disks, anything that can take out two disks can probably take out three just as easily. These physical issues include repairmen who use a hammer as a CPU installation tool (this is not a joke). -- http://www.coker.com.au/selinux/ My NSA Security Enhanced Linux packages http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark http://www.coker.com.au/postal/Postal SMTP/POP benchmark http://www.coker.com.au/~russell/ My home page -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: email server - how to
Andreas John wrote: > >> Best to use 2U machines with the maximum number of disks IMHO. A 2U >> machine should be able to have 5 disks. > > > I say: 9 Disks without problems. e.g. pcicase > http://www.pcicase.de/catalog/produktweb/IPC-C2-X/IPC-C2D.htm > > The question is with that many disks is a single raid 5 going to be enough redundancy... Thats an awful lot of data to loose if 2 drives fail. May be worth thinking about RAID6 or a couple of RAID5 arrays striped
Re: email server - how to
Andreas John wrote: > >> Best to use 2U machines with the maximum number of disks IMHO. A 2U >> machine should be able to have 5 disks. > > > I say: 9 Disks without problems. e.g. pcicase > http://www.pcicase.de/catalog/produktweb/IPC-C2-X/IPC-C2D.htm > > The question is with that many disks is a single raid 5 going to be enough redundancy... Thats an awful lot of data to loose if 2 drives fail. May be worth thinking about RAID6 or a couple of RAID5 arrays striped -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: email server - how to
Best to use 2U machines with the maximum number of disks IMHO. A 2U machine should be able to have 5 disks. I say: 9 Disks without problems. e.g. pcicase http://www.pcicase.de/catalog/produktweb/IPC-C2-X/IPC-C2D.htm
Re: email server - how to
On Tue, 29 Jun 2004 23:16, Michelle Konzack <[EMAIL PROTECTED]> wrote: > Am 2004-06-29 09:49:12, schrieb Gustavo Polillo: > > Hi everybody.. > > > > sorry by may english, but I am brazilian > > I'd like to know how the email server works with thousand users... > > lvm??? how storage de inbox with 500Mb size and with 1 users??? > > Sorry, but nobody puts 10.000 $USER with 500 MByte each on one Box ! > I am at freenet.de and they have around 300 Mailbox-Servers... Why not? The last ISP I worked for had >200,000 users per 2U back-end machine. The quotas were quite a lot lower than 500M, but the trick was in making sure that the vast majority of accounts were not near the quota. > I think, the limit today is at 1000 $USER for redunancy and secrity. That's an expensive way to run things. $10K for a server means that each user eats a $10 start-up cost plus 1/1000 of the on-going maintenance and support costs for the server. > AND (!!!) a Bunch of little Athlon 2600 with a SCSI-Raid (3-4 Disks > of 147 GB) are cheaper as one Big machine. Best to use 2U machines with the maximum number of disks IMHO. A 2U machine should be able to have 5 disks. It seems that ATA disks are available in larger sizes than SCSI. One supplier I checked offers IDE disks up to 300G in size, but SCSI only to 147. Get 5 * 300G disks in a RAID-5 and you have 1.2T in 2U. That should fit 10,000 users with a 500M quota each with room to spare. -- http://www.coker.com.au/selinux/ My NSA Security Enhanced Linux packages http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark http://www.coker.com.au/postal/Postal SMTP/POP benchmark http://www.coker.com.au/~russell/ My home page
Re: email server - how to
On Tue, 29 Jun 2004 22:49, "Gustavo Polillo" <[EMAIL PROTECTED]> wrote: >I'd like to know how the email server works with thousand users... Quite easily usually. When you get to 200,000 users things get more difficult, but 1000 is not much by today's standards. > lvm??? how storage de inbox with 500Mb size and with 1 users??? If your quota is 500M per user then the average should be something less than 50M, which for 10,000 users would give 500G of storage use. A RAID-5 of 12 disks of 100G or more in size should do the job nicely. To keep the average use well below the maximum you want to have some procedures for removing unwanted accounts and messages. EG delete mail that hasn't been read for a certain period of time, and close accounts that have a certain level of inactivity. Otherwise lots of people will subscribe to mailing lists and disappear leaving their 500M quota to fill. LVM probably isn't the best way to expand. Beyond certain limits it becomes inconvenient to have a single server manage it all. So you have front end servers that relay the inbound mail to the correct back-end server and use Perdition to proxy POP and IMAP to the correct back-end server. This way you can have many small back-end servers doing the mail storage instead of one big server. If you want to have a million accounts then it's cheaper and easier to have 6 servers for $10,000 each rather than one server for $1M. -- http://www.coker.com.au/selinux/ My NSA Security Enhanced Linux packages http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark http://www.coker.com.au/postal/Postal SMTP/POP benchmark http://www.coker.com.au/~russell/ My home page
Re: email server - how to
Am 2004-06-29 09:49:12, schrieb Gustavo Polillo: > > > Hi everybody.. > > sorry by may english, but I am brazilian > I'd like to know how the email server works with thousand users... lvm??? > how storage de inbox with 500Mb size and with 1 users??? Sorry, but nobody puts 10.000 $USER with 500 MByte each on one Box ! I am at freenet.de and they have around 300 Mailbox-Servers... I think, the limit today is at 1000 $USER for redunancy and secrity. AND (!!!) a Bunch of little Athlon 2600 with a SCSI-Raid (3-4 Disks of 147 GB) are cheaper as one Big machine. >thanks. >Gustavo. Greetings Michelle -- Linux-User #280138 with the Linux Counter, http://counter.li.org/ Michelle Konzack Apt. 917 ICQ #328449886 50, rue de Soultz MSM LinuxMichi 0033/3/8845235667100 Strasbourg/France IRC #Debian (irc.icq.com) signature.pgp Description: Digital signature
email server - how to
Hi everybody.. sorry by may english, but I am brazilian I'd like to know how the email server works with thousand users... lvm??? how storage de inbox with 500Mb size and with 1 users??? thanks. Gustavo.
Re: email server - how to
Best to use 2U machines with the maximum number of disks IMHO. A 2U machine should be able to have 5 disks. I say: 9 Disks without problems. e.g. pcicase http://www.pcicase.de/catalog/produktweb/IPC-C2-X/IPC-C2D.htm -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: email server - how to
On Tue, 29 Jun 2004 23:16, Michelle Konzack <[EMAIL PROTECTED]> wrote: > Am 2004-06-29 09:49:12, schrieb Gustavo Polillo: > > Hi everybody.. > > > > sorry by may english, but I am brazilian > > I'd like to know how the email server works with thousand users... > > lvm??? how storage de inbox with 500Mb size and with 1 users??? > > Sorry, but nobody puts 10.000 $USER with 500 MByte each on one Box ! > I am at freenet.de and they have around 300 Mailbox-Servers... Why not? The last ISP I worked for had >200,000 users per 2U back-end machine. The quotas were quite a lot lower than 500M, but the trick was in making sure that the vast majority of accounts were not near the quota. > I think, the limit today is at 1000 $USER for redunancy and secrity. That's an expensive way to run things. $10K for a server means that each user eats a $10 start-up cost plus 1/1000 of the on-going maintenance and support costs for the server. > AND (!!!) a Bunch of little Athlon 2600 with a SCSI-Raid (3-4 Disks > of 147 GB) are cheaper as one Big machine. Best to use 2U machines with the maximum number of disks IMHO. A 2U machine should be able to have 5 disks. It seems that ATA disks are available in larger sizes than SCSI. One supplier I checked offers IDE disks up to 300G in size, but SCSI only to 147. Get 5 * 300G disks in a RAID-5 and you have 1.2T in 2U. That should fit 10,000 users with a 500M quota each with room to spare. -- http://www.coker.com.au/selinux/ My NSA Security Enhanced Linux packages http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark http://www.coker.com.au/postal/Postal SMTP/POP benchmark http://www.coker.com.au/~russell/ My home page -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: email server - how to
On Tue, 29 Jun 2004 22:49, "Gustavo Polillo" <[EMAIL PROTECTED]> wrote: >I'd like to know how the email server works with thousand users... Quite easily usually. When you get to 200,000 users things get more difficult, but 1000 is not much by today's standards. > lvm??? how storage de inbox with 500Mb size and with 1 users??? If your quota is 500M per user then the average should be something less than 50M, which for 10,000 users would give 500G of storage use. A RAID-5 of 12 disks of 100G or more in size should do the job nicely. To keep the average use well below the maximum you want to have some procedures for removing unwanted accounts and messages. EG delete mail that hasn't been read for a certain period of time, and close accounts that have a certain level of inactivity. Otherwise lots of people will subscribe to mailing lists and disappear leaving their 500M quota to fill. LVM probably isn't the best way to expand. Beyond certain limits it becomes inconvenient to have a single server manage it all. So you have front end servers that relay the inbound mail to the correct back-end server and use Perdition to proxy POP and IMAP to the correct back-end server. This way you can have many small back-end servers doing the mail storage instead of one big server. If you want to have a million accounts then it's cheaper and easier to have 6 servers for $10,000 each rather than one server for $1M. -- http://www.coker.com.au/selinux/ My NSA Security Enhanced Linux packages http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark http://www.coker.com.au/postal/Postal SMTP/POP benchmark http://www.coker.com.au/~russell/ My home page -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: email server - how to
Am 2004-06-29 09:49:12, schrieb Gustavo Polillo: > > > Hi everybody.. > > sorry by may english, but I am brazilian > I'd like to know how the email server works with thousand users... lvm??? > how storage de inbox with 500Mb size and with 1 users??? Sorry, but nobody puts 10.000 $USER with 500 MByte each on one Box ! I am at freenet.de and they have around 300 Mailbox-Servers... I think, the limit today is at 1000 $USER for redunancy and secrity. AND (!!!) a Bunch of little Athlon 2600 with a SCSI-Raid (3-4 Disks of 147 GB) are cheaper as one Big machine. >thanks. >Gustavo. Greetings Michelle -- Linux-User #280138 with the Linux Counter, http://counter.li.org/ Michelle Konzack Apt. 917 ICQ #328449886 50, rue de Soultz MSM LinuxMichi 0033/3/8845235667100 Strasbourg/France IRC #Debian (irc.icq.com) signature.pgp Description: Digital signature
email server - how to
Hi everybody.. sorry by may english, but I am brazilian I'd like to know how the email server works with thousand users... lvm??? how storage de inbox with 500Mb size and with 1 users??? thanks. Gustavo. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
