549 reputation
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bio website eecs.harvard.edu/~keith
location Cambridge, MA
age 49
visits member for 5 years, 2 months
seen Jul 31 at 20:29
Building file systems for fun and for profit

Jul
30
comment Doing an rm -rf on a massive directory tree takes hours
Hmm. I probably came off as being too contrary above. The original poster must be using Linux, and there really isn't a well-proven Linux file system that does snapshots---although btrfs and nilfs look interesting for the future. So as a practical matter, I agree---better to use block-based snapshots.
Jul
30
comment Doing an rm -rf on a massive directory tree takes hours
Block-based snapshots are not uniquely good in this case. A number of file systems---WAFL and ZFS come immediately to mind---also provide good performance for snapshot delete. They treat snapshots as first class file system objects. So rather than iterating (slowly) over millions of files to determine which blocks to free, they only have to look a the block-list associated with the snapshot.
Jul
14
comment Reliability of ssd drives
There are high-end SSDs that address all of these. The one I'm familiar with off the top of my head is the Zeus IOPS from STEC. It's a hot-swappable Fibre Channel drive built with SLC flash. Due to smart firmware and heavy over-provisioning of flash, it can do more than 10,000 write IOPS/sec. It's also rather price---several thousand dollars for a 256GB drive. While that may make it seem prohibitive, the theory is that enough traditional disks to deliver those IOPS would cost even more.
Jul
14
comment Reliability of ssd drives
The better enterprise SSDs have comparable warranties---For example STEC's Zeus. The spec sheet lists the warranty as 5 years. See stec-inc.com/downloads/flash_datasheets/iopsdatasheet.pdf
Jul
9
comment Most efficient RAID configuration with 6 disks?
You don't say how you will be implementing RAID. Do you have a controller of some sort? Will you be using software RAID? While this won't affect the theoretical trade-offs between different RAID level's, it may help make the best decision for your system based on the reliability and quality of your RAID engine