Russell Coker wrote:
I have some servers that are giving inadequate disk performance for Maildir mail spools. They are running kernel 2.4.19 (2.4.20 upgrade is planned) and using ReiserFS for everything that's important.The umem.com folks sell a device that we have tested and benchmarked reiserfs on. If I could get Edward to format benchmarks in a way that conveys that information that is relevant to persons reading them, I would post them on our mailing list....
At this stage it is impossible for me to replace disks, RAID controllers, or anything else really significant.
What I am thinking of doing is using a kernel that supports data journalling which should increase performance, but still probably won't give me enough. So I am thinking of using an "external journal" (or using software RAID to put the part of the partition containing the journal on a different device).
The device containing the journal would be something much faster than physical media. I have been doing some research on non-volatile memory devices. I only found one company producing disks that are RAM based with battery backup, and they seem to start at $10K (too expensive - probably because they are much larger than I need, I need 128M at most, they provide 2G). I found many companies selling flash memory, but that only takes a million writes (that'll last about an hour for the use I plan). I found one company selling PC-Card devices that have two batterys for backup, but that requires getting a PCI controller for PC-Card's (something I haven't tried before).
Does anyone know of an affordable ($1000 or less) device that can survive unexpected power outages of at least 24 hours duration, can commit a write in less than 1ms, supports unlimited writes, and connects to a IDE or SCSI bus (or PCI if there's a suitable Linux driver).
Hans
