Hey all, we're in the process of checking out alternatives to our index storage. We're currently storing indexes on a NetApp Metrocluster which works fine, but is very expensive. We're planning a few different setups and doing some actual performance tests on them. Does anyone know some of the IO patterns of the indexes? For instance: - mostly random reads or linear reads/writes? - average size of reads and writes? - how many read/writes on average for a specific mailbox size? Anyone do any measurements of this kind? Alternatively, does anyone have any experience with other redundant storage options? Im thinking things like MooseFS, DRBD, etc? regards, Cor
Indexes are very random, mostly read, some writes if using dovecot-lda (ej: dbox). The average size is rather small, maybe 5 KB in our setup. Bandwith is rather low, 20-30 MB/sec We are using HP LeftHand for our replicated storage needs. Regards Javier El 11/05/2012 08:41, Cor Bosman escribi?:> Hey all, we're in the processof checking out alternatives to our index storage. We're currently storing indexes on a NetApp Metrocluster which works fine, but is very expensive. We're planning a few different setups and doing some actual performance tests on them.> > Does anyone know some of the IOpatterns of the indexes? For instance:> > - mostly random reads orlinear reads/writes?> - average size of reads and writes? > - how manyread/writes on average for a specific mailbox size?> > Anyone do anymeasurements of this kind?> > Alternatively, does anyone have anyexperience with other redundant storage options? Im thinking things like MooseFS, DRBD, etc?> > regards, > > Cor
Hi javier,> > > Indexes are very random, mostly read, some writes if using > dovecot-lda (ej: dbox). The average size is rather small, maybe 5 KB in > our setup. Bandwith is rather low, 20-30 MB/secEven without LDA/LMTP dovecot-imap needs to write right? It would need to update the index every time an imap connect happens and new mails are found in the mail store. Cor
> Even without LDA/LMTP dovecot-imap needs to write right? It would > need to update the index every time an imap connect happens and > new mails are found in the mail store.Well of course. Indexes are also updated when flags are modified, moved a messages, delete a message, etc.. But in my setup there are 65% reads and the rest writes Regards Javier> > Cor >
On 5/11/2012 1:41 AM, Cor Bosman wrote:> Hey all, we're in the process of checking out alternatives to our index storage. We're currently storing indexes on a NetApp Metrocluster which works fine, but is very expensive. We're planning a few different setups and doing some actual performance tests on them.Hi Cor,> Does anyone know some of the IO patterns of the indexes? For instance: > > - mostly random reads or linear reads/writes? > - average size of reads and writes? > - how many read/writes on average for a specific mailbox size? > > Anyone do any measurements of this kind?Mail is always a random IO workload, unless your mailbox count is 1, whether accessing indexes or mail files. Regarding the other two questions, you'll likely need to take your own measurements.> Alternatively, does anyone have any experience with other redundant storage options? Im thinking things like MooseFS, DRBD, etc?You seem to be interested in multi-site clustering/failover solutions, not simply redundant storage. These two are clustering software solutions but DRBD is not suitable for multi-site use, and MooseFS doesn't seem to be either. MooseFS is based heavily on FUSE, so performance will be far less than optimal. MooseFS is a distributed filesystem, and as with all other distributed/cluster filesystems its metadata performance will suffer, eliminating maildir as a mail store option. Can you provide more specifics on your actual storage architecture needs? -- Stan