Hello, I'm in the process of finalizing the spec for my new dovecot VM, and this is the last question I need to address... I've read until I'm just about decided on XFS, but I have no experience with it (been using reiserfs on my old box (@ 8 yrs old now), and never had a problem (knock on wood), but considering its current situation (little to no development support for reasons everyone is aware of), I've decided now is the time to switch. It came down to XFS or EXT4, and I like what I've read about XFS, but am unsure how to tune it (or even if I should). I've decided to use mdbox for storage (been using maildir), and will enable SIS for attachments. So, anyone (Stan?) have any suggestions? Should I go with EXT4? Or XFS with just the defaults? Or XFS with one or more tuned parameters? Appreciate any suggestions (including links to docs dealing with tuning XFS for my mail storage conditions that are written more at the layman level) or comments from anyone experienced using both... Thanks, -- Best regards, Charles
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Charles Marcus said the following on 02/05/2013 13:16:> So, anyone (Stan?) have any suggestions? Should I go with EXT4? Or XFS with > just the defaults? Or XFS with one or more tuned parameters?Expecially when you are working in virtual environments, keep in mind the concept of "I/O cascading" The bottleneck of virtual environment are often IOPS (I/O per second), so a VM that has a light footprint of IOPS will have a better performance. The I/O cascading is in essence the muptiplying factor of each disk write at application level. Consider a SQL UPDATE statement: you have date written on database and trasaction log. Each file will have its mtime updated. If the underlying file system is transactional you will have double writes for actual file and transaction log... And so on. The first and obvious advice (quite a default nowdays with SSD storage) is to mount the FS with noatime. But I think that is obvius as "do backups". Ciao, luigi - -- / +--[Luigi Rosa]-- \ If one morning I walked on top of the water across the Potomac River, the headline that afternoon would read "President Can't Swim". --Lyndon B. Johnson -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with undefined - http://www.enigmail.net/ iEYEARECAAYFAlGCU+IACgkQ3kWu7Tfl6ZSLjwCgt2MJu5wqXOj4Mt3UdsvmaFc1 cO0AnAmxKtsJ0evmrVXUlnY6e06WtLIL =Rf7R -----END PGP SIGNATURE-----
Il 02/05/2013 13:16, Charles Marcus ha scritto:> Hello, > > I'm in the process of finalizing the spec for my new dovecot VM, and > this is the last question I need to address... > > I've read until I'm just about decided on XFS, but I have no experience > with it (been using reiserfs on my old box (@ 8 yrs old now), and never > had a problem (knock on wood), but considering its current situation > (little to no development support for reasons everyone is aware of), > I've decided now is the time to switch. It came down to XFS or EXT4, and > I like what I've read about XFS, but am unsure how to tune it (or even > if I should). > > I've decided to use mdbox for storage (been using maildir), and will > enable SIS for attachments. > > So, anyone (Stan?) have any suggestions? Should I go with EXT4? Or XFS > with just the defaults? Or XFS with one or more tuned parameters? > > Appreciate any suggestions (including links to docs dealing with tuning > XFS for my mail storage conditions that are written more at the layman > level) or comments from anyone experienced using both... > > Thanks, >Hi, I'm using XFS for mail storage (Maildir type) and it works fine and better than ext4 (especially if you storage is very large). My mount options are: "rw,noatime,attr2,delaylog,nobarrier,inode64,noquota" and I'm running it on RHEL 6.4 For more information you can read the RHEL documentation: https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/xfsmain.html https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Performance_Tuning_Guide/main-fs.html Ciao -- Alessio Cecchi is: @ ILS -> http://www.linux.it/~alessice/ on LinkedIn -> http://www.linkedin.com/in/alessice Assistenza Sistemi GNU/Linux -> http://www.cecchi.biz/ @ PLUG -> ex-Presidente, adesso senatore a vita, http://www.prato.linux.it
Zitat von Charles Marcus <CMarcus at media-brokers.com>:> Hello, > > I'm in the process of finalizing the spec for my new dovecot VM, and > this is the last question I need to address... > > I've read until I'm just about decided on XFS, but I have no > experience with it (been using reiserfs on my old box (@ 8 yrs old > now), and never had a problem (knock on wood), but considering its > current situation (little to no development support for reasons > everyone is aware of), I've decided now is the time to switch. It > came down to XFS or EXT4, and I like what I've read about XFS, but > am unsure how to tune it (or even if I should). > > I've decided to use mdbox for storage (been using maildir), and will > enable SIS for attachments. > > So, anyone (Stan?) have any suggestions? Should I go with EXT4? Or > XFS with just the defaults? Or XFS with one or more tuned parameters? > > Appreciate any suggestions (including links to docs dealing with > tuning XFS for my mail storage conditions that are written more at > the layman level) or comments from anyone experienced using both...IMHO if you say "VM" than the filesystem inside the guest doesn't matter that much. The difference of ext4/xfs are mostly the knowledge and adjustability for special (high-end) hardware and the like. With a Hypervisor providing some standard I/O channel and hiding/handling the hardware details itself, most of the differences are gone. With this in mind your question should maybe more of "what filesystem is more Hypervisor friendly". For this i would suspect the simpler the better, so i would choose ext4. Regards Andreas -------------- next part -------------- A non-text attachment was scrubbed... Name: smime.p7s Type: application/pkcs7-signature Size: 6144 bytes Desc: S/MIME Cryptographic Signature URL: <http://dovecot.org/pipermail/dovecot/attachments/20130502/10aad4f0/attachment.bin>
Am 02.05.2013 17:31, schrieb Charles Marcus:> On 2013-05-02 10:45 AM, Reindl Harald <h.reindl at thelounge.net> wrote: >> "man mount" is very generic and doe snot cover any option >> there is also no "man mount.ntfs" while "mount.ntfs" command exists > > ? > > man mount, at least mine, shows first the FILESYSTEM INDEPENDENT MOUNT OPTIONS, then as you scroll down, you'll get > to all of the additional filesystem specific options, ie, for xfs... > > So, not sure what you mean by 'does not cover any option'...typo - meant "does not cover ALL options" someone has to write the manpages, there are millions of options all over the software-world which did it not make into manpages google for "xfs delaylog" leads to http://xfs.org/index.php/XFS_FAQ http://xfs.org/index.php/XFS_FAQ#Q:_I_want_to_tune_my_XFS_filesystems_for_.3Csomething.3E For mount options, the only thing that will change metadata performance considerably are the logbsize and delaylog mount options so how can it be redhat-specific if it is mentioned upstream? -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 263 bytes Desc: OpenPGP digital signature URL: <http://dovecot.org/pipermail/dovecot/attachments/20130502/3637012f/attachment.bin>
On 5/2/2013 6:16 AM, Charles Marcus wrote: ...> I've decided to use mdbox for storage (been using maildir), and will > enable SIS for attachments. > > So, anyone (Stan?) have any suggestions? Should I go with EXT4? Or XFS > with just the defaults? Or XFS with one or more tuned parameters? > > Appreciate any suggestions (including links to docs dealing with tuning > XFS for my mail storage conditions that are written more at the layman > level) or comments from anyone experienced using both...>From a filesystem perspective mdbox is little different from maildir asthey both exhibit lots of small random IOs. With either one aligning the filesystem to the RAID stripe is problematic as it can create spindle hotspots and increase free space fragmentation. If you're using a vmdk stripe alignment isn't possible anyway as VMware ignores hardware device geometry WRT vmdks. Although the EXT developers have been working overtime the last few years trying to borrow/steal/duplicate the advanced performance features of XFS, they have a very long way to go. The parallel performance of EXT is far behind as well as file allocation/layout and free space management, to name a few. My recommendation is to use XFS with the defaults, but add "inode64" to the mount options in /etc/fstab. This enables the modern allocator which clusters files around their parent directory within an allocation group. It's the default allocator in very recent upstream kernels but not in most currently shipping distro kernels. It decreases seek latency between metadata and file operations, and better manages on disk space. In short, XFS will yield superior mail performance to EXT4 in a multiuser environment. There are currently no mail workload tuning docs in the world of XFS that I'm aware of. I've been intending to write such a doc for the XFS.org FAQ for some time but it hasn't happened yet. -- Stan
On 2013-05-03 10:21 AM, Charles Marcus <CMarcus at Media-Brokers.com> wrote:>> How about the other filesystems I snipped? If you have a large number >> of filesystems atop the same RAID, some of them being XFS, this could >> create a head thrashing problem under high load increasing latency >> and thus response times. > > Ouch... > > This ESXi host also hosts 2 server 2008R2 vms...Or did you mean just the other filesystems in this linux VM? Yes, they are all on the same RAID. The only purpose of the other xfs volume - snaps- is to hold snapshots of /var for email backup purposes - so, rsnapshot will initiate an LVM snapshot, take the backup, then remove the snapshot. /snaps is not used for anything else, and it is the only other xfs filesystem. The others are either ext4 (/ and /boot) or ext2 (/tmp, /var/tmp and /var/log)... -- Best regards, Charles
On 5/2/2013 4:16 AM, Charles Marcus wrote:> Hello, > > I'm in the process of finalizing the spec for my new dovecot VM, and > this is the last question I need to address... > > I've read until I'm just about decided on XFS, but I have no > experience with it (been using reiserfs on my old box (@ 8 yrs old > now), and never had a problem (knock on wood), but considering its > current situation (little to no development support for reasons > everyone is aware of), I've decided now is the time to switch. It came > down to XFS or EXT4, and I like what I've read about XFS, but am > unsure how to tune it (or even if I should). > > I've decided to use mdbox for storage (been using maildir), and will > enable SIS for attachments. > > So, anyone (Stan?) have any suggestions? Should I go with EXT4? Or XFS > with just the defaults? Or XFS with one or more tuned parameters? > > Appreciate any suggestions (including links to docs dealing with > tuning XFS for my mail storage conditions that are written more at the > layman level) or comments from anyone experienced using both... > > Thanks, >For what it's worth if you can afford it I'd use SSD drives. My server screams since I went to SSD.