On Thursday 29 March 2007 03:09:33 Remy Blank wrote: > Boyd Stephen Smith Jr. wrote: > >> <troll> > >> ZFS? > >> </troll> > > > > You say troll, I say possibility; I'll certainly consider it. > > Actually, I would be very interested in using ZFS for my data. > > The "troll" was more about the fact that the ZFS license was explicitly > designed to be GPL-2 incompatible, hence preventing it from being > included into Linux (it would require a clean-room rewrite from the specs). > > > However, the demos that I've seen about ZFS stress how easy it is to > > administer, and all the LVM-style features it has. Personally, > > I've /very/ comfortable with LVM and am of the opinion that such features > > don't actually belong at the "filesystem" layer. > > I haven't made the step to LVM and am still using a plain old RAID-1 > mirror. I'm not that comfortable adding one more layer to the data path, > and one more difficulty in case of hard disk failure. > > > I need to good general purpose filesystem, what matters most to be is: > > 1) Online growing of the filesystem, with LVM I use this a lot, I won't > > consider a filesystem I can't grow while it is in active use. > > 2) Journaling or other techniques (FFS from the *BSD world does something > > they don't like to call journaling) that reduce the frequency of full > > fscks. > > 3) All-round performance, and I don't mind it using extra CPU time or > > memory to make filesystem performance better, I have both to spare. > > 4) Storage savings (like tail packing or transparent compression) > > I completely agree with 1) and 2), and 3) and 4) are nice to haves. What > I like in ZFS is the data integrity check, i.e. every block gets a > checksum, and it can auto-repair in a RAID-Z configuration, something > that RAID-1 cannot.
RAID-3?/5/6 can self-repair like this, but the checksumming is done at the stripe, rather than inode level. Since I use HW RAID-6 across 10 drives, I'm not that concerned with this done at the filesystem level. Even without the extra disks, you can use SW RAID across partitions on a single (or small number of) disk(s). [(Ab)uses of SW RAID like this are not something I'd always recommend, but can provide the integrity checks you desire.] Also, EVMS provides a BBR (bad block relocatation) target, that can work around isolated disk failures. > 5) Reliable data integrity checks and self-healing capability. Overall, I see this as something I'd rather see done at the block device level, instead of the filesystem level. Surely, a filesystem should not shy away from sanity checks that can be done with little overhead besides CPU time, but adding a checksum to each block might be a little overkill. -- Boyd Stephen Smith Jr. ,= ,-_-. =. [EMAIL PROTECTED] ((_/)o o(\_)) ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-' http://iguanasuicide.org/ \_/
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