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1.
Heterogeneous Disk Arrays (HDAs) allow resource sharing of their hardware by multiple RAID levels. RAID1 (mirrored disks) and RAID5 (distributed parity arrays)
are the two RAID levels considered in this study. They are both single disk failure tolerant (1DFT), but differ significantly in their efficiency in processing database workloads. The goal of the study is to maximize the
number of Virtual Array (VA) allocations in HDA. We develop an analysis to estimate the load per VA based on a few parameters: the fraction of accesses
to small versus large blocks and the fraction of updates versus reads. A VA is allocated according to the RAID level, which
minimizes the anticipated load based on input parameters. Operation in normal and degraded mode is considered for comparison
purposes, but in fact allocations are carried out using the higher load in degraded mode to ensure that single disk failures
will not result in overload. We report on parametric studies to gain insight into circumstances leading to a RAID1 or RAID5
classification. An allocation experiment with a synthetic workload is used to demonstrate the superiority of HDA with respect
to purely RAID1 or RAID5 disk arrays. This analytic study can be extended to 2DFT arrays, namely RAID6 versus 3-way replication. 相似文献
2.
Distributed redundant array of inexpensive disks (RAID) is often embedded in a cluster architecture. In a centralized RAID subsystem, the false sharing problem does not exist, because the disk array allows only mutually exclusive access by one user at a time. However, the problem does exist in a distributed RAID architecture, because multiple accesses may occur simultaneously in a distributed environment. This problem will seriously limit the effectiveness of collective I/O operations in network-based, cluster computing. Traditional accesses to disks in a RAID are done at block level. The block granularity is large, say 32 KB, often resulting in false sharing among fragments in the block. The false sharing problem becomes worse when the block size or the stripe unit becomes too large. To solve this problem, we propose an adaptive sector grouping approach to accessing a distributed RAID. Each sector has a fine grain of 512 B. Multiple sectors are grouped together to match with the data block size. The grouped sector has a variable size that can be adaptively adjusted by software. Benchmark experiments reveal the positive effects of this adaptive access scheme on the performance of a RAID. Our scheme can reduce the collective I/O access time without increasing the buffer size. Both theoretical analysis and experimental results demonstrate the performance gain in using grouped sectors for fast access of distributed RAID. 相似文献
3.
A new layout method Prime-groups is proposed to evenly distribute parity groups for declustered RAID. Prime-groups satisfies most of the layout goals for a good declustered RAID layout. For the goals that are not satisfied, it is near optimal. A new layout goal maximal write and reconstruction parallelism is also proposed. If a layout satisfies the new goal, all the surviving disks can be read in parallel and can be rewritten in parallel during reconstruction and reconfiguration. Prime-groups satisfies the new goal when the write request begins in the first disk of the array. It is also near optimal in term of declustering ratio when p is a prime. Prime-groups can compliment the layouts proposed by Alvarez et al. [2] for the criteria to obtain a good layout is quite different between Prime-groups and those proposed by Alvarez et al. [2]. 相似文献
4.
We report the synthesis of phosphorescent divalent osmium complexes of the form [Os(N-N)2(L-L) or Os(L-L)2(N-N)]2+ (PF6)2 where N-N is a derivative of 1,10-phenanthroline, and L-L is a diarsine or diphosphine ligand: 1,2-bis(dimethylphosphino)ethane, 1,2-bis(dicyclohexylphosphino)ethane, or 1,2-bis(dimethylarseno)benzene. X-ray structures have been determined, luminescent and electrochemical properties have been measured and DFT calculations have been performed on the complexes. The emission lifetime of complexes of structure Os(II)(L-L)2(N-N) are longer than the those of Os(II)(N-N)2(L-L). The DFT calculations show that there is significant mixing of the π−π∗ into the dπ−π∗ charge-transfer state for the complexes of the form Os(II)(L-L)2(N-N) resulting in a longer lived excited state. Through DFT calculations we were able to conclude that the HOMO of the complexes is a d orbital on the osmium while the LUMO is the b1(ψ) π∗ system of the phenanthroline. However, we found that the HOMO did not have the correct symmetry to enable strong charge transfer to the phenanthroline to be observed, and the strong MLCT transition observed in the spectra is the metal d HOMO(−1) to the b1 π∗ LUMO of the phenanthroline. 相似文献
5.
Alexander Thomasian 《Cluster computing》2006,9(4):475-484
Disk mirroring or RAID level 1 stores the same data twice, on two independent disks, to ensure that all single disk failures
can be tolerated. This high storage overhead is acceptable in view of the drop in storage cost per gigabyte and rapidly increasing
disk capacities. Disk access time, on the other hand, is improving at a very slow pace, so that another important advantage
of disk mirroring is the doubling of the disk access bandwidth in processing read requests. Efficient routing of read requests
to disks and local disk scheduling can be used to improve performance even further. We are primarily concerned with two RAID1
configurations: (i) source-initiated routing with the independent queues—IQ method; (ii) destination-initiated routing with the shared queue—SQ method. Static, dynamic, and affinity-based (AB) routing methods are used to distribute requests with the IQ method. We compare
the performance of various IQ and SQ based routing policies using a random number-driven simulation. While there is some improvement
in performance with the more sophisticated routing policies, performance is dominated by the local disk scheduling policy.
The SQ method allows resource sharing, so that it tends to outperform the IQ based routing, but it requires the scheduler
to keep track of the state of the disk drives. As a further means to improve performance, we consider the effect of prioritizing
reads with respect to writes, transposed data allocation, and replicating data more than twice.
We acknowledge the support of NSF through Grant 0105485 in Computer Systems Architecture.
Alexander Thomasian (ACM) is a Professor of Computer Science at New Jersey Institute of Technology. He was a faculty member at Case Western University
and University of Southern California and an adjunct professor at Columbia University, while a Research Staff Member at the
IBM T. J. Watson Research Center (1985–1998). He received his PhD in Computer Science from UCLA. Dr. Thomasian’s research
has more recently been focused on indexing high-dimensional datasets and especially the performance of storage systems. He
is the author of Database Concurrency Control: Methods, Performance, and Analysis, Kluwer 1996. Dr. Thomasian is a Fellow of IEEE. 相似文献
6.
Li W Zhu S Li J Huang Y Zhou R Fan X Yang H Gong X Eissa NT Jahnen-Dechent W Wang P Tracey KJ Sama AE Wang H 《PloS one》2011,6(2):e16945
Background
A liver-derived protein, fetuin-A, was first purified from calf fetal serum in 1944, but its potential role in lethal systemic inflammation was previously unknown. This study aims to delineate the molecular mechanisms underlying the regulation of hepatic fetuin-A expression during lethal systemic inflammation (LSI), and investigated whether alterations of fetuin-A levels affect animal survival, and influence systemic accumulation of a late mediator, HMGB1.Methods and Findings
LSI was induced by endotoxemia or cecal ligation and puncture (CLP) in fetuin-A knock-out or wild-type mice, and animal survival rates were compared. Murine peritoneal macrophages were challenged with exogenous (endotoxin) or endogenous (IFN-γ) stimuli in the absence or presence of fetuin-A, and HMGB1 expression and release was assessed. Circulating fetuin-A levels were decreased in a time-dependent manner, starting between 26 h, reaching a nadir around 24–48 h, and returning towards base-line approximately 72 h post onset of endotoxemia or sepsis. These dynamic changes were mirrored by an early cytokine IFN-γ-mediated inhibition (up to 50–70%) of hepatic fetuin-A expression. Disruption of fetuin-A expression rendered animals more susceptible to LSI, whereas supplementation of fetuin-A (20–100 mg/kg) dose-dependently increased animal survival rates. The protection was associated with a significant reduction in systemic HMGB1 accumulation in vivo, and parallel inhibition of IFN-γ- or LPS-induced HMGB1 release in vitro.Conclusions
These experimental data suggest that fetuin-A is protective against lethal systemic inflammation partly by inhibiting active HMGB1 release. 相似文献7.
We present gmblock, a block-level storage sharing system over Myrinet which uses an optimized I/O path to transfer data directly
between the storage medium and the network, bypassing the host CPU and main memory bus of the storage server. It is device
driver independent and retains the protection and isolation features of the OS. We evaluate the performance of a prototype
gmblock server and find that: (a) the proposed techniques eliminate memory and peripheral bus contention, increasing remote
I/O bandwidth significantly, in the order of 20–200% compared to an RDMA-based approach, (b) the impact of remote I/O to local
computation becomes negligible, (c) the performance characteristics of RAID storage combined with limited NIC resources reduce
performance. We introduce synchronized send operations to improve the degree of disk to network I/O overlapping. We deploy
the OCFS2 shared-disk filesystem over gmblock and show gains for various application benchmarks, provided I/O scheduling can
eliminate the disk bottleneck due to concurrent access. 相似文献
8.
《Animal : an international journal of animal bioscience》2021,15(3):100158
Aggression resulting from mixing to establish a dominance hierarchy is a major welfare concern for group-housed sows. The associated stress can negatively impact aspects of reproductive performance. Objectives of this study were to investigate associations between 1) age at first service (AFS) and mixing aggression intensity in first parity sows, 2) mixing aggression intensity and reproductive performance within and between parity one and parity two, and 3) mixing aggression intensity, floor type during gestation and reproductive performance. Gilts (n = 160, hereafter referred to as sows) were mixed into stable groups of eight unfamiliar individuals approximately 4 days after artificial insemination, housed on fully slatted concrete (CON; n = 80) floor uncovered or covered with rubber slat mats (RUB; n = 80), and followed through two parities. Skin lesions (SLMIX; a proxy for the intensity of mixing aggression), were scored post mixing in each parity according to severity (0 = no lesions to 5 = severe lesions) on five body regions (ear, neck, hindquarter, rump, and belly) on the left and right sides, and at the tail/anogenital region. Total SLMIX score was calculated for each sow. Data on reproductive performance traits were acquired retrospectively from farm records for both parities. Two analyses were performed: 1) data from each parity were analysed separately and 2) SLMIX score in parity one was used to predict reproductive performance in parity two. Lower AFS was associated with a lower SLMIX score in parity one (P = 0.031). There was no association between SLMIX score and reproductive performance in parity one, while sows with higher SLMIX score in parity two had a higher proportion of piglets dead during lactation (P = 0.027) and a longer cycle length (P = 0.003) in parity two. Sows with higher SLMIX scores in parity one had more non-productive days (P < 0.001) in parity two. Concrete sows had a higher SLMIX score than RUB sows in parity one (P = 0.015), but not in parity two. In addition, CON sows had a higher proportion of piglets born dead (P = 0.013) compared with RUB sows in parity two. Mixing aggression has a negative influence on reproductive performance within parities, and it may also have a long-term negative carry-over effect on reproductive performance in subsequent parities. Serving gilts at younger ages could help to minimize the intensity of aggression at mixing, while housing on rubber flooring has beneficial implications for their reproductive performance. 相似文献
9.
The dimethylaminopyridine (DMAP) promoted reaction between [Os(bpy)2(CO)(OTf)]OTf (where ) and methylene chloride is reported. C-Cl bond breaking of a solvent molecule leads to the formation of the [Os(bpy)2(CO)(Cl)]OTf complex. The reactivity and redox properties of [Os(bpy)2(CO)(OTf)]OTf were investigated by means of room- and low-temperature electrochemical experiments. In CH2Cl2, at low temperature, the complex undergoes two 1e electrochemical and chemical reversible reductions (ErEr mechanism), but at room temperature a more complex electrochemical mechanism is observed, leading to the electro-synthesis of [Os(bpy)2(CO)(Cl)]OTf via electrochemical reversible and chemical irreversible reduction processes (ErCi mechanism). The DMAP nucleophilicity was used to produce the new [Os(bpy)2(CO)(Br)]OTf and [Os(bpy)2(CO)(I)]OTf complexes which have been fully characterized. 相似文献
10.
Sukanya Luang Jung-Il Cho Bancha Mahong Rodjana Opassiri Takashi Akiyama Kannika Phasai Juthamath Komvongsa Nobuhiro Sasaki Yan-ling Hua Yuki Matsuba Yoshihiro Ozeki Jong-Seong Jeon James R. Ketudat Cairns 《The Journal of biological chemistry》2013,288(14):10111-10123
Glycosylation is an important mechanism of controlling the reactivities and bioactivities of plant secondary metabolites and phytohormones. Rice (Oryza sativa) Os9BGlu31 is a glycoside hydrolase family GH1 transglycosidase that acts to transfer glucose between phenolic acids, phytohormones, and flavonoids. The highest activity was observed with the donors feruloyl-glucose, 4-coumaroyl-glucose, and sinapoyl-glucose, which are known to serve as donors in acyl and glucosyl transfer reactions in the vacuole, where Os9BGlu31 is localized. The free acids of these compounds also served as the best acceptors, suggesting that Os9BGlu31 may equilibrate the levels of phenolic acids and carboxylated phytohormones and their glucoconjugates. The Os9BGlu31 gene is most highly expressed in senescing flag leaf and developing seed and is induced in rice seedlings in response to drought stress and treatment with phytohormones, including abscisic acid, ethephon, methyljasmonate, 2,4-dichlorophenoxyacetic acid, and kinetin. Although site-directed mutagenesis of Os9BGlu31 indicated a function for the putative catalytic acid/base (Glu169), catalytic nucleophile residues (Glu387), and His386, the wild type enzyme displays an unusual lack of inhibition by mechanism-based inhibitors of GH1 β-glucosidases that utilize a double displacement retaining mechanism. 相似文献
11.
《Animal : an international journal of animal bioscience》2020,14(6):1196-1203
The small intestine is an important digestive organ and plays a vital role in the life of a pig. We tested the hypothesis that the length of the small intestine is related to growth performance and intestinal functions of piglets. A total of 60 piglets (Duroc × Landrace × Yorkshire), weaned at day 21, were fed an identical diet during a 28-day trial. At the end of the study, all piglets were sacrificed, dissected and grouped according to small intestine lengths (SILs), either short small intestine (SSI), middle small intestine (MSI) or long small intestine (LSI), respectively. Positive relationships between SIL and BW, average daily gain (ADG), average daily feed intake (ADFI) and gain-to-feed ratios (G : F) were observed. Final BW, ADG, ADFI and G : F significantly increased (P < 0.05) in MSI and LSI piglets compared with SSI piglets. Short small intestine and MSI had greater jejunal mucosa sucrase and alkaline phosphatase activities (P < 0.05) than LSI piglets. The mRNA level of solute carrier family 2 member 2 (Slc2a2) in the jejunal mucosa of SSI piglets was the greatest. The MSI piglets had a greater (P < 0.05) ileal villus height than other piglets and greater (P < 0.05) villus height-to-crypt depth ratios than LSI piglets. However, the LSI piglets had a greater (P < 0.05) ileal crypt depth than SSI piglets. No significant differences in duodenal, jejunal, caecal and colonic morphologies were detected among the groups. Moreover, luminal acetate, propionate, butyrate and total short-chain fatty acid contents were greater (P < 0.05) in SSI and MSI piglets than those in LSI piglets. In addition, there was greater serum glucose concentration in MSI piglets than other piglets. Serum albumin concentration in SSI piglets was the lowest. In conclusion, these results indicate that SIL was significantly positively associated with growth performance, and in terms of intestinal morphology and mucosal digestive enzyme activity, the piglets with a medium length of small intestine have better digestion and absorption properties. 相似文献
12.
13.
[Os(phen)(RaaiR′)2](PF6)2 [phen = 1,10-phenanthroline, RaaiR′ = 1-alkyl-2-(arylazo)imidazole, p-R-C6H4-NN-C3H2-NN-1-R′, where R = H (a), Me (b), Cl (c) and R′ = Me (2), Et (3), CH2Ph (4) have been synthesized from the reaction of cis-trans-cis-[OsBr2(RaaiR′)2] with phen in the presence of aqueous AgNO3 in ethanol. The structure of [Os(phen)(ClaaiEt)2](PF6)2 was confirmed by X-ray diffraction study. Electronic spectra exhibit a strong MLCT band at 490-512 nm along with weak transition at longer wavelength 865-880 nm. Cyclic voltammetry of the complexes shows two metal redox couples, Os(III)/Os(II) at 0.9-1.0 V and Os(IV)/Os(III) at 1.4-1.6 V versus SCE, and three successive ligand reductions. The EHMO calculation using crystallographic parameters of the complex has been compared with analogous Ru and Os complexes. A correlation between electronic properties and MO results is also reported. 相似文献
14.
Felix Hupfeld Björn Kolbeck Jan Stender Mikael Högqvist Toni Cortes Jonathan Martí Jesús Malo 《Cluster computing》2009,12(2):175-188
A lease is a token which grants its owner exclusive access to a resource for a defined span of time. In order to be able to tolerate failures, leases need to be coordinated by distributed processes. We present FaTLease, an algorithm for fault-tolerant lease negotiation in distributed systems. It is built on the Paxos algorithm for distributed consensus, but avoids Paxos’ main performance bottleneck of requiring persistent state. This property makes our algorithm particularly useful for applications that can not dispense any disk bandwidth. Our experiments show that FaTLease scales up to tens of thousands of concurrent leases and can negotiate thousands of leases per second in both LAN and WAN environments. 相似文献
15.
《Inorganica chimica acta》1988,147(2):251-256
The compound, diiodooctacarbonyldiosmium(I), [Os2(CO)8I2], has been prepared by a route involving only atmospheric pressures. Its structure has been determined by X-ray crystallography. The crystals are tetragonal with a = 11.791(2), c = 23.583(4) Å, Z = 8, Dc = 3.48 Mg m−3. A total of 1637 reflections were collected out to θ = 25° on a CAD4 diffractometer in ω—2θ mode using Mo Kα (λ = 0.7107 Å) radiation. Lp and empirical absorption corrections were applied. The structure was solved in the space group I41cd using conventional heavy atom methods and refined to R = 0.0477 [Rw = 0.0424, w = (σ2F)−1]. The molecule of [Os2(CO)8l2] has two crystallographically equivalent halves joined by a single OsOs bond of length 2.947(3) )Å. There are no bridging ligands. The geometry about each osmium is pseudo-octahedral and the iodine atoms occupy equatorial positions with an OsI distance of 2.767(3) Å. The equatorial ligands on one osmium atom are staggered with respect to the equatorial ligands on the other osmium atom. 相似文献
16.
Bacterial lipases from family I.1 and I.2 catalyze the hydrolysis of triacylglycerol between 25–45°C and are used extensively as biocatalysts. The lipase from Proteus mirabilis belongs to the Proteus/psychrophilic subfamily of lipase family I.1 and is a promising catalyst for biodiesel production because it can tolerate high amounts of water in the reaction. Here we present the crystal structure of the Proteus mirabilis lipase, a member of the Proteus/psychrophilic subfamily of I.1lipases. The structure of the Proteus mirabilis lipase was solved in the absence and presence of a bound phosphonate inhibitor. Unexpectedly, both the apo and inhibitor bound forms of P. mirabilis lipase were found to be in a closed conformation. The structure reveals a unique oxyanion hole and a wide active site that is solvent accessible even in the closed conformation. A distinct mechanism for Ca2+ coordination may explain how these lipases can fold without specific chaperones. 相似文献
17.
《Animal : an international journal of animal bioscience》2019,13(3):622-630
Understanding how critical sow live-weight and back-fat depth during gestation are in ensuring optimum sow productivity is important. The objective of this study was to quantify the association between sow parity, live-weight and back-fat depth during gestation with subsequent sow reproductive performance. Records of 1058 sows and 13 827 piglets from 10 trials on two research farms between the years 2005 and 2015 were analysed. Sows ranged from parity 1 to 6 with the number of sows per parity distributed as follows: 232, 277, 180, 131, 132 and 106, respectively. Variables that were analysed included total born (TB), born alive (BA), piglet birth weight (BtWT), pre-weaning mortality (PWM), piglet wean weight (WnWT), number of piglets weaned (Wn), wean to service interval (WSI), piglets born alive in subsequent farrowing and sow lactation feed intake. Calculated variables included the within-litter CV in birth weight (LtV), pre-weaning growth rate per litter (PWG), total litter gain (TLG), lactation efficiency and litter size reared after cross-fostering. Data were analysed using linear mixed models accounting for covariance among records. Third and fourth parity sows had more (P<0.05) TB, BA and heavier BtWT compared with gilts and parity 6 sow contemporaries. Parities 2 and 3 sows weaned more (P<0.05) piglets than older sows. These piglets had heavier (P<0.05) birth weights than those from gilt litters. LtV and PWM were greater (P<0.01) in litters born to parity 5 sows than those born to younger sows. Sow live-weight and back-fat depth at service, days 25 and 50 of gestation were not associated with TB, BA, BtWT, LtV, PWG, WnWT or lactation efficiency (P>0.05). Heavier sow live-weight throughout gestation was associated with an increase in PWM (P<0.01) and reduced Wn and lactation feed intake (P<0.05). Deeper back-fat in late gestation was associated with fewer (P<0.05) BA but heavier (P<0.05) BtWT, whereas deeper back-fat depth throughout gestation was associated with reduced (P<0.01) lactation feed intake. Sow back-fat depth was not associated with LtV, PWG, TLG, WSI or piglets born alive in subsequent farrowing (P>0.05). In conclusion, this study showed that sow parity, live-weight and back-fat depth can be used as indicators of reproductive performance. In addition, this study also provides validation for future development of a benchmarking tool to monitor and improve the productivity of modern sow herd. 相似文献
18.
Vinicius Zamprogno Mota Gustavo Senra Gonçalves de Carvalho Adilson David da Silva Luiz Antônio Sodré Costa Patrícia de Almeida Machado Elaine Soares Coimbra Carmen Veríssima Ferreira Silvia Mika Shishido Alexandre Cuin 《Biometals》2014,27(1):183-194
Synthesis, characterization, DFT studies and biological assays of new gold(I) and gold(III) complexes of benzimidazole are reported. Molecular and structural characterizations of the compounds were based on elemental (C, H and N) and thermal (TG–DTA) analyses, and FT-IR and UV–Visible spectroscopic measurements. The structures of complexes were proposed based DFT calculations. The benzimidazole compounds (Lig1 and Lig2) and the gold complexes were tested against three Leishmania species related to cutaneous manifestations of leishmaniasis. The free benzimidazole compounds showed no leishmanicidal activity. On the other hand, the gold(I and III) complexes have shown to possess significant activity against Leishmania in both stages of parasite, and the gold(III) complex with Lig2 exhibited expressive leishmanicidal activity with IC50 values below 5.7 μM. Also, the gold complexes showed high leishmania selectivity. The gold(I) complex with Lig1, for example, is almost 50 times more toxic for the parasite than for macrophages. Besides the leishmanicidal activity, all complexes exhibited toxic effect against SK-Mel 103 and Balb/c 3T3, cancer cells. 相似文献
19.
The complexes [(L)Os(η6-Cym)Cl](PF6), Cym = p-cymene and L = bis(1-methylimidazol-2-yl)ketone (bik) or bis(1-methylimidazol-2-yl)glyoxal (big), were obtained and characterized with respect to spectroscopy, crystal structure (big complex) and (spectro)electrochemical behaviour at variable temperatures. DFT calculations confirm the structure of [(big)Os(η6-Cym)Cl]+ with imidazolyl-N-bonded OsII in a boat-shaped seven-membered chelate ring with small N-Os-N angles (<84°). Reduction of this compound proceeds reversibly to a neutral complex of the α-semidione radical anion ligand big−; EPR and IR spectroelectrochemistry indicate very little participation from the heavy metal in the spin distribution. The analogous [(bik)Os(η6-Cym)Cl]+ could not be reduced reversibly to the ketyl radical complex but displayed a more reversible oxidation at high potential. 相似文献
20.