> On Wed, Sep 15, 2010 at 09:15:13AM +0530, Shuvam Misra wrote: >> Dear Bron, >> >> > http://www.newegg.com/Product/Product.aspx?Item=N82E16822148413 >> > >> > 2TB - US $109. >> >> Don't want to nit-pick here, but the effective price we pay is about >> ten times this. > > Yeah, so? It's going down. That's a large number of attachments > we're talking about there. > >> To set up a mail server with a few TB of disk space, >> we usually land up deploying a separate chassis with RAID controllers >> and >> a RAID array, with FC connections from servers, etc, etc. All this adds >> up to about $1,000/TB of usable space if you're using something like the >> "low-end" IBM DS3400 box or Dell/EMC equivalent. This is even with >> inexpensive 7200RPM SATA-II drives, not 15KRPM SAS drives. > > Hmm... our storage units with metadata on SSD come in about $1200/TB. > Yes, that sounds about right. That's including hot spares, RAID1 on > everything (including the SSDs), scads of processor and memory. > Obviously multiply that by two for replication, and add in a bit of > extra for backups and I'm happy to arrive at a figure of approximately > $3000 per terabyte of actual email. > >> And most of our customers actually double this cost because they keep >> two >> physically identical chassis for redundancy. (We recommend this too, >> because we can't trust a single RAID 5 array to withstand controller or >> PSU failures.) In that case, it's $2000/TB. > > And because it's nice not to have downtime when you're doing > maintainence. I replaced an entire drive unit today, including > about 4 hours downtime on one of our servers as the system was > swamped with IO creating new filesystems and initialising the > drives. The users didn't see a thing, and repliation is now > fully operational again. > >> And you do reach 5-10 TB of email store quite rapidly --- our company >> has many corporate clients (< 500 email users) whose IMAP store has >> reached 4TB. No one wants to enforce disk quotas (corporate policy), >> and most users don't want to delete emails on their own. > > So you save, what, 50%. Does that sound about right? Do you have > statistics on how much space you'd save with this theoretical > patch? > >> We keep hearing the logic that storage is cheap, and stories of cloud >> storage through Amazon, unlimited mailboxes on Gmail, are reinforcing >> the belief. But at the ground level in mid-market corporate IT budgets, >> storage costs in data centres (as against inside desktops) are still >> too high to be trivial, and their prices have only little to do with >> the prices of raw SATA-II drives. A fully-loaded DS3400 costs a little >> over $12,000 in India, with a full set of 1TB SATA-II drives from IBM, >> but even with high cost of IBM drives, the drives themselves contribute >> less than 30% of the total cost. > > You're buying a few months. Usage grows to fill the available storage, > whatever it is. And you can only pull this piece of magic once. > >> If we really want to put our collective money where our mouth is, and >> deliver the storage-is-cheap promise at the ground level, we need to >> rearchitect every file server and IMAP server to work in map-reduce mode >> and use disks inside desktops. Anyone game for this project? :) > > You could buy as much benefit much more quickly by gzipping the > individual email files. Either a filesystem that stores files > compressed, or a cyrus patch to do that and unpack files on the > fly if the body was read. Along with most/all headers in the I guess much more efficient than a compressing filesystem would be a compressing and de-duping filesystem or disk storage in this case. Has anyone tried this with a Cyrus message store with lots of "corporate message data" stored on it? Simon ---- Cyrus Home Page: http://www.cyrusimap.org/ List Archives/Info: http://lists.andrew.cmu.edu/pipermail/info-cyrus/
