DHCP and Pt-Pt DSL links?
Hi all, In running up a new DSL connection today, I came across an "interesting" situation w.r.t. DHCP and point-to-point links. The planned implementation is to have the Netgear DG632 ADSL modem do the PPPoA but pass (by DHCP) the single fixed-IP address to the Linux box on the ethernet (this is the gateway/firewall). I.e. the modem is doing the PPPoA but bridging the IP. This appears to be confounded by the PPP link having its remote endpoint not in the same network as the local endpoint. So when the ADSL modem responds to the DHCP request it supplies a local address in one network but has (and I assume provides via the DHCP "routers" attribute) a gateway which is in a completely different subnet. The result is that the interface on the Linux box (FWIW, Debian "sarge", using ISC dhclient) is configured with the correct local address but no default gateway. OTOH, if we use static configuration of the ethernet interface and set it up as a point-to-point ethernet link all works OK - but we're figuring this isn't really a cool long-term proposal as it obviously won't pick up any changes in the ISP-assigned attributes (e.g. gateway, DNS servers). Anyone know if either: (a) We're flogging a dead horse in trying to use DHCP like this? (b) There's a way of getting DHCP to configure pt-pt ethernet? Thanks, Neale. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: RAID-1 to RAID-5 online migration?
> PS: i wouldn't recommend software raid 5 if you care about performance. i > am going to convert one of my raid-5 machines (4 x 80GB barracudas) to > raid-1 (2 x 200GB barracudas) very soon because i'm unhappy with the > performance(*)...if i had a spare approx $600AUD, i'd buy an IDE raid card > with at least 32MB non-volatile cache memory and that would give me raid-5 > with decent performance, but it's just not worth that much to me for a > workstation. Any tests on RAID-5 being slower than RAID-1 (a problem in software-raid implementation?) ? I have always thought RAID-5 is the fastest... But I suppose you will get a performance raise due to changing disks to more faster ones (more volume almost always gives more speed, except for the cases when that new volume is made by adding plates/surfaces/heads) Dmitry -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
RAID-6 vs. RAID-5?
Hi, could anybody comment, what's the current inofficial quality of RAID6 vs. RAID5? The kernel help does read as if it's pretty beta still. Has anybody bothered trying? Thanks! -- Best regards, Kilian signature.asc Description: Dies ist ein digital signierter Nachrichtenteil
Re: RAID-1 to RAID-5 online migration?
On Monday 06 September 2004 13.38, Dmitry Golubev wrote: > > PS: i wouldn't recommend software raid 5 if you care about performance. > > i am going to convert one of my raid-5 machines (4 x 80GB barracudas) > > to raid-1 (2 x 200GB barracudas) very soon because i'm unhappy with the > > performance(*)...if i had a spare approx $600AUD, i'd buy an IDE raid > > card with at least 32MB non-volatile cache memory and that would give > > me raid-5 with decent performance, but it's just not worth that much to > > me for a workstation. > > Any tests on RAID-5 being slower than RAID-1 (a problem in software-raid > implementation?) ? I have always thought RAID-5 is the fastest... But I RAID5 does need more computation than RAID1, so if you have a CPU bottleneck RAID5 will always be slower (assuming RAID5 is computed on the main CPU.) For reading, RAID5 is very fast, since access can be spread over many disks. OTOH each read from RAID5 touches n - 1 disks, so concurrent reads tend to be not as fast as some may expect them to be. Big caches are mandatory here! For writing, RAID5 tends to be noticeably slower than RAID1, especially for writes smaller than stripe size, because a write actually is a read-recompute-write cycle. If you have battery backed RAM on your RAID controller, or you're just willing to risk it, RAID5 can profit a lot from a big write cache. (And even with read cache only, bigger is better for writing, too, as the non-written part of a stripe might just be in the cache.) For RAID 1, you can get quite close to the theoretical max bandwidth: 1 x disk speed on writing, and 2 x disk speed for reading. (Of course, available bus bandwidth etc. will limit this, and there is some minimal management overhead, but RAID1 is quite simple, after all.) -- Today is Prickle-Prickle, the 30th day of Bureaucracy in the YOLD 3170 pgpFjxn3o7XKh.pgp Description: PGP signature
Re: RAID-1 to RAID-5 online migration?
At 03:35 PM 9/6/04 +0200, Adrian 'Dagurashibanipal' von Bidder wrote: >For writing, RAID5 tends to be noticeably slower than RAID1, especially for >writes smaller than stripe size, because a write actually is a >read-recompute-write cycle. If ur looking for a fast RAID product that's reasonably priced I'ld take a look at NetCell's SyncRAID product (http://www.netcell.com/) which uses a 64 bit RAID-3 variant they call RAID XL. It got a good review from Tom's Hardware Guide and it looks like they've really solved the read-calc-write problem of RAID-5. -- REMEMBER THE WORLD TRADE CENTER ---=< WTC 911 >=-- "...ne cede males" 0100 -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
